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ΓòÉΓòÉΓòÉ 1. HTML 4.0 Reference ΓòÉΓòÉΓòÉ
HTML 4.0 Reference
HTML 4.0 became a W3C Recommendation in December of 1997. The new HTML standard
provides a number of significant improvements over previous versions of the
language while emphasizing the concepts of accessibility and structural markup.
Contents
What's New in HTML 4.0
A summary of the new features in HTML 4.0 and a look at the key
concepts behind the new standard.
Structure of an HTML 4.0 Document
An explanation of elements, tags, and attributes, and how they are
used in an HTML 4.0 document.
Organizational List of HTML 4.0 Elements
All HTML 4.0 elements organized by their function.
Alphabetical List of HTML 4.0 Elements
All HTML 4.0 elements listed alphabetically.
HTML 4.0 Entities
All character entity references in HTML 4.0 along with their numeric
character references and rendering in your browser.
ΓòÉΓòÉΓòÉ 1.1. Credits and other info. ΓòÉΓòÉΓòÉ
Original HTML documents by Liam Quinn <liam@htmlhelp.com>
Conversion to INF format by Mark Healey <edantes@cts.com>
This file is meant to be concatenated with CSS.inf. Some of the links in this
file lead to panels in that file.
To concatenate the files place the files anywhere in your "BOOKSHELF" path and
create a program object with the fields in the properties ("settings" in pre
4.0 versions) notebook thus:
Program Page
Path and file name
view.exe
Parameters
html40.inf+css.inf
Icon Page ("general" in pre 4.0 versions)
Title
what ever you want
Current Icon
Drop any icon you like (I hope it is the one I made for this.)
ΓòÉΓòÉΓòÉ 1.2. What's New in HTML 4.0 ΓòÉΓòÉΓòÉ
What's New in HTML 4.0
o New Elements in HTML 4.0
o Separation of Structure and Presentation
o Accessibility
o Internationalization
o Style Sheets
o Client-side Scripting
o Frames
o Advanced Tables
═══ 1.2.1. New Elements in HTML 4.0 ═══
New Elements in HTML 4.0
The following elements are new in HTML 4.0:
o ABBR - Abbreviation
o ACRONYM - Acronym
o BDO - BiDi override
o BUTTON - Button
o COL - Table column
o COLGROUP - Table column group
o DEL - Deleted text
o FIELDSET - Form control group
o FRAME - Frame
o FRAMESET - Frameset
o IFRAME - Inline frame
o INS - Inserted text
o LABEL - Form field label
o LEGEND - Fieldset caption
o NOFRAMES - Frames alternate content
o NOSCRIPT - Alternate script content
o OBJECT - Object
o OPTGROUP - Option group
o Q - Short quotation
o S - Strike-through text
o SPAN - Generic inline container
o TBODY - Table body
o TFOOT - Table foot
o THEAD - Table head
ΓòÉΓòÉΓòÉ 1.2.2. Separation of Structure and Presentation ΓòÉΓòÉΓòÉ
Separation of Structure and Presentation
By deprecating many presentational features from HTML 3.2 and adding hooks for
style sheets , HTML 4.0 encourages separating a document's structure from its
presentation. This concept is key to understanding HTML 4.0.
When authors use HTML to markup a document's structure and style sheets to
suggest the document's presentation, they can more easily achieve the
device-independence that helped bring HTML its initial popularity. A document
with a rich structure can be presented in many different ways on different
media, allowing the document to adjust to new technologies such as phone or
in-car aural browsers. The separation of content and presentation also allows
authors to change the presentation of an entire site by editing a single style
sheet, providing significant advantages in site maintenance.
ΓòÉΓòÉΓòÉ 1.2.3. Accessibility ΓòÉΓòÉΓòÉ
Accessibility
Many of HTML 4.0's improvements in the area of accessibility follow from its
emphasis on the separatoin of structure and presentation. When HTML is used
structurally, a document can adapt to different browsing environments,
accommodating large fonts, special colors, speech synthesizers, and Braille
tactile feedback devices. This adaptability allows blind, low-vision,
colorblind, and cognitively-challenged users access to the Web, opening a door
for the world's 600 million disabled people.
HTML 4.0 includes many new elements and attributes aimed at improving the Web's
accessibility. The multi-dimensional nature of HTML tables has long posed
problems for non-visual browsing, but new attributes on the TABLE, TH, and TD
elements allow table summaries and a more explicit association between a cell
and its header information. These attributes give non-visual browsers the
ability to render a cell's header information, possibly in an abbreviated form,
before giving the cell's content.
New elements in HTML 4.0 also bring accessibility improvements to forms. The
new FIELDSET element allows form controls to be grouped together and the LEGEND
element provides a caption for the group. By grouping related form controls,
authors allow those with non-visual browsers to more easily navigate
complicated forms. As well, the new LABEL element associates a text label with
a form control so that users can more easily determine what information is
required in a given field.
Other accessibility improvements include full image descriptions through the
LONGDESC attribute on the IMG element, rich alternatives to images and videos
through the OBJECT element, and richer alternatives to image maps through a new
content model for the MAP element.
ΓòÉΓòÉΓòÉ 1.2.4. Internationalization ΓòÉΓòÉΓòÉ
Internationalization
To allow representation of the world's languages, HTML 4.0 adopts the Universal
Character Set as its character set. Previous versions of HTML were restricted
to ISO-8859-1, a character set that only handled some western European
languages. The Universal Character Set is character-by-character equivalent to
Unicode 2.0 and contains characters for almost all of the world's languages.
The LANG and DIR attributes are new in HTML 4.0 and apply to almost all
elements. These attributes allow authors to specify the language and
directionality of text. The BDO element allows authors to override the
bidirectional algorithm used when right-to-left text such as Hebrew is
presented.
HTML 4.0 also offers new entities for easy entry of mathematical symbols and
Greek letters as well as other special characters.
ΓòÉΓòÉΓòÉ 1.2.5. Style Sheets ΓòÉΓòÉΓòÉ
Style Sheets
HTML 4.0 adds new hooks for style sheets, which suggest how a document is
presented. The new ID, CLASS, and STYLE attributes allow style information to
be attached to specific elements. The LINK and STYLE elements have new TYPE and
MEDIA attributes for specifying the style sheet language and target media,
respectively.
ΓòÉΓòÉΓòÉ 1.2.6. Client-side Scripting ΓòÉΓòÉΓòÉ
Client-side Scripting
HTML 4.0 embraces client-side scripting through the addition of a number of new
attributes. The SCRIPT element now includes attributes for specifying the
scripting language, embedding an external script, and deferring execution of a
script. As well, a number of event attributes have been added to enable
execution of a script upon events such as the user clicking an element,
pressing a key, moving the mouse over an element, or changing the value of a
form control.
The NOSCRIPT element, also new in HTML 4.0, provides alternate content for
browsers with client-side scripting disabled or not supported.
ΓòÉΓòÉΓòÉ 1.2.7. Frames ΓòÉΓòÉΓòÉ
Frames
The inclusion of frames in HTML 4.0 gives authors the ability to present
multiple documents in one window. The frames model used in HTML 4.0 is not
changed from the flawed frames model originally proposed by Netscape.
ΓòÉΓòÉΓòÉ 1.2.8. Advanced Tables ΓòÉΓòÉΓòÉ
Advanced Tables
The simple table model of HTML 3.2 is expanded in HTML 4.0 to include row and
column groups, greater flexibility in defining a table's rules, and
accessibility improvements. The use of row groups (THEAD, TFOOT, TBODY) allows
visual browsers to render static header and footer rows with scrollable body
rows, thus improving the readability of large tables.
ΓòÉΓòÉΓòÉ 1.2.9. HTML 4.0 Deprecated Features ΓòÉΓòÉΓòÉ
HTML 4.0 Deprecated Features
A number of elements and attributes are deprecated in HTML 4.0 as an indication
that other methods of accomplishing the same task are preferred. Deprecated
features may become obsolete in future versions of HTML, though browsers that
support the features will likely continue to support them. Deprecated features
are included in HTML 4.0 Transitional and HTML 4.0 Frameset but not HTML 4.0
Strict.
Many presentational elements and attributes are deprecated in favor of style
sheets, which allow authors to suggest a presentation with more flexibility and
without sacrificing accessibility. Presentational attributes that cannot
currently be replaced with style sheets are in most cases not deprecated.
The following elements are deprecated in favor of style sheets :
o BASEFONT - Base font change
o CENTER - Centered block
o FONT - Font change
o S - Strike-through text
o STRIKE - Strike-through text
o U - Underlined text
link reftype=hd res=.The following elements are also deprecated:
o APPLET - Java applet (deprecated in favor of OBJECT)
o DIR - Directory list (deprecated in favor of UL)
o ISINDEX - Input prompt (deprecated in favor of INPUT)
o MENU - Menu list (deprecated in favor of UL)
ΓòÉΓòÉΓòÉ 1.3. Structure of an HTML 4.0 Document ΓòÉΓòÉΓòÉ
Structure of an HTML 4.0 Document
o Elements and Tags
o Attributes
o Special Characters
o Comments
o A Complete HTML 4.0 Document
o Validating your HTML
ΓòÉΓòÉΓòÉ 1.3.1. Elements and Tags ΓòÉΓòÉΓòÉ
Elements and Tags
Elements are the structures that describe parts of an HTML document. For
example, the P element represents a paragraph while the EM element gives
emphasized content.
An element has three parts: a start tag, content, and an end tag. A tag is
special text--"markup"--that is delimited by "<" and ">". An end tag includes a
"/" after the "<". For example, the EM element has a start tag, <EM>, and an
end tag, </EM>. The start and end tags surround the content of the EM element:
<EM>This is emphasized text</EM>
Element names are always case-insensitive, so <em>, <eM>, and <EM> are all the
same.
Elements cannot overlap each other. If the start tag for an EM element appears
within a P, the EM's end tag must also appear within the same P element.
Some elements allow the start or end tag to be omitted. For example, the LI end
tag is always optional since the element's end is implied by the next LI
element or by the end of the list:
<UL>
<LI>First list item; no end tag
<LI>Second list item; optional end tag included</LI>
<LI>Third list item; no end tag
</UL>
Some elements have no end tag because they have no content. These elements,
such as the BR element for line breaks, are represented only by a start tag and
are said to be empty.
ΓòÉΓòÉΓòÉ 1.3.1.1. HTML 4.0 Block-Level Elements ΓòÉΓòÉΓòÉ
HTML 4.0 Block-Level Elements
Most HTML 4.0 elements permitted within the BODY are classified as either
block-level elements or inline elements. Block-level elements typically contain
inline elements and other block-level elements. When rendered visually,
block-level elements usually begin on a new line.
The following are defined as block-level elements in HTML 4.0:
o ADDRESS - Address
o BLOCKQUOTE - Block quotation
o CENTER - Centered block
o DIR - Directory list
o DIV - Generic block-level container
o DL - Definition list
o FIELDSET - Form control group
o FORM - Interactive form
o H1 - Level-one heading
o H2 - Level-two heading
o H3 - Level-three heading
o H4 - Level-four heading
o H5 - Level-five heading
o H6 - Level-six heading
o HR - Horizontal rule
o ISINDEX - Input prompt
o MENU - Menu list
o NOFRAMES - Frames alternate content
o NOSCRIPT - Alternate script content
o OL - Ordered list
o P - Paragraph
o PRE - Preformatted text
o TABLE - Table
o UL - Unordered list
The following elements may also be considered block-level elements since they
may contain block-level elements:
o DD - Definition description
o DT - Definition term
o FRAMESET - Frameset
o LI - List item
o TBODY - Table body
o TD - Table data cell
o TFOOT - Table foot
o TH - Table header cell
o THEAD - Table head
o TR - Table row
The following elements may be used as either block-level elements or inline
elements. If used as inline elements (e.g., within another inline element or a
P), these elements should not contain any block-level elements.
o APPLET - Java applet
o BUTTON - Button
o DEL - Deleted text
o IFRAME - Inline frame
o INS - Inserted text
o MAP - Image map
o OBJECT - Object
o SCRIPT - Client-side script
ΓòÉΓòÉΓòÉ 1.3.1.2. HTML 4.0 Inline Elements ΓòÉΓòÉΓòÉ
HTML 4.0 Inline Elements
Most HTML 4.0 elements permitted within the BODY are classified as either
block-level elements or inline elements. Inline elements typically may only
contain text and other inline elements. When rendered visually, inline elements
do not usually begin on a new line.
The following are defined as inline elements in HTML 4.0:
o A - Anchor
o ABBR - Abbreviation
o ACRONYM - Acronym
o B - Bold text
o BASEFONT - Base font change
o BDO - BiDi override
o BIG - Large text
o BR - Line break
o CITE - Citation
o CODE - Computer code
o DFN - Defined term
o EM - Emphasis
o FONT - Font change
o I - Italic text
o IMG - Inline image
o INPUT - Form input
o KBD - Text to be input
o LABEL - Form field label
o Q - Short quotation
o S - Strike-through text
o SAMP - Sample output
o SELECT - Option selector
o SMALL - Small text
o SPAN - Generic inline container
o STRIKE - Strike-through text
o STRONG - Strong emphasis
o SUB - Subscript
o SUP - Superscript
o TEXTAREA - Multi-line text input
o TT - Teletype text
o U - Underlined text
o VAR - Variable
The following elements may be used as either block-level elements or inline
elements. If used as inline elements (e.g., within another inline element or a
P), these elements should not contain any block-level elements.
o APPLET - Java Applet
o BUTTON - Button
o DEL - Deleted text
o IFRAME - Inline frame
o INS - Inserted text
o MAP - Image map
o OBJECT - Object
o SCRIPT - Client-side script
ΓòÉΓòÉΓòÉ 1.3.2. Attributes ΓòÉΓòÉΓòÉ
Attributes
An element's attributes define various properties for the element. For example,
the IMG element takes a SRC attribute to provide the location of the image and
an ALT attribute to give alternate text for those not loading images:
<IMG SRC="wdglogo.gif" ALT="Web Design Group">
An attribute is included in the start tag only--never the end tag--and takes
the form Attribute-name="Attribute-value". The attribute value is delimited by
single or double quotes. The quotes are optional if the attribute value
consists solely of letters in the range A-Z and a-z, digits (0-9), hyphens
("-"), and periods (".").
Attribute names are case-insensitive, but attribute values may be
case-sensitive.
ΓòÉΓòÉΓòÉ 1.3.2.1. HTML 4.0 Attribute Values ΓòÉΓòÉΓòÉ
HTML 4.0 Attribute Values
There are various kinds of attribute values in HTML 4.0. This document
describes common types of values.
CDATA
Attribute values of type CDATA are made up of a sequence of characters that may
include entities. Line feeds are ignored while each carriage return and tab is
replaced with a space. Browsers may ignore leading and trailing whitespace
within the attribute value.
CDATA attribute values are typically case-sensitive, though this is not the
case with all attributes that take CDATA values.
ID and NAME
Attribute values of type ID and NAME must begin with a letter in the range A-Z
or a-z and may be followed by letters (A-Za-z), digits (0-9), hyphens ("-"),
underscores ("_"), colons (":"), and periods ("."). These values are
case-sensitive.
IDREF and IDREFS
IDREF and IDREFS values refer to values of other elements' ID attributes. An
IDREF value is a single ID while an IDREFS value is a space-separated list of
IDs. IDREF and IDREFS are case-sensitive.
Number
Number attribute values are numbers made of at least one digit in the range
0-9.
Text
Text attribute values are CDATA values intended to be human readable strings.
URI
URI attribute values are Uniform Resource Identifiers (URIs), as defined in the
URI Internet-Draft, a work-in-progress that is expected to replace RFC 1738 and
RFC 1808.
URI attribute values may include full URIs such as http://www.htmlhelp.com/. as
well as relative URIs such as foo.html and ../foo/.
While parts of a URI may be case-insensitive, in general URI values are
case-sensitive.
Color
Color attribute values give a color definition. The value can be any
hexadecimal number, specified according to the sRGB color space, or one of
sixteen color names. Hexadecimal numbers must be prefixed by a "#" character.
The case-insensitive color names and their sRGB values are as follows:
Color Name sRGB Value
Black #000000
Silver #C0C0C0
Gray #808080
White #FFFFFF
Maroon #800000
Red #FF0000
Purple #800080
Fuchsia #FF00FF
Green #008000
Lime #00FF00
Olive #808000
Yellow #FFFF00
Navy #000080
Blue #0000FF
Teal #008080
Aqua #00FFFF
Note that the hexadecimal form is better supported than the color names for the
color attributes of BODY.
Pixels
These attribute values are integers that represent a number of pixels.
Length
Length attribute values may be either an integer--interpreted as a number of
pixels--or a percentage of the horizontal or vertical space. The value 50%
means half the available space while 50 means 50 pixels.
MultiLength and MultiLengths
MultiLength attribute values may be an integer in pixels, a percentage of the
horizontal or vertical space, or a relative length expressed as i* where i is
an integer. In allotting space, a browser first allots pixel and percentage
lengths, then divides the remaining space among all elements with a relative
length. An element with a length of 3* will be allotted three times the space
of an element with length 1*. The value * is equivalent to 1* and is often used
to mean "fill the remaining space."
A MultiLengths value is a comma-separated list of MultiLength values.
ContentType and ContentTypes
These attribute values are content types (also known as media types or MIME
types) of a linked or embedded resource. Values of type ContentType give a
single content type while values of type ContentTypes give a comma-separated
list of content types. Content types are case-insensitive.
Commonly used content types include text/html, image/jpeg, model/vrml,
video/quicktime, application/java, text/css, and text/javascript. Many common
content types are registered at the IANA.
LanguageCode
Attribute values of type LanguageCode specify a language code according to RFC
1766. Examples of language codes include en for English, en-US for American
English, and ja for Japanese. Whitespace is not allowed in the language code,
which is case-insensitive.
Charset and Charsets
These attribute values specify character encodings of linked resources. Values
of type Charset give a single character encoding while values of type Charsets
give a space- and/or comma-separated list of character encodings. Character
encodings are case-insensitive.
Examples of character encodings include ISO-8859-1, SHIFT_JIS, and UTF-8. A
list of registered character encodings is available at the IANA.
Character
Character attribute values take a single Unicode character. The character may
be specified with an entity.
Datetime
Datetime attribute values give a date and time in the format
YYYY-MM-DDThh:mm:ssTZD where YYYY is a four-digit year, MM is a two-digit month
(01 through 12), DD is a two-digit day (01 through 31), hh is a two-digit
hour(00 through 23), mm is a two-digit minute (00 through 59), ss is a
two-digit second (00 through 59), and TZD is the time zone designator. Note
that the T separating the date from the time must appear literally and is
case-sensitive.
The time zone designator may be one of the following:
o Z (case-sensitive), which indicates Universal Coordinated Time (UTC,
basically the same as GMT);
o +hh:mm, the time ahead of UTC in hours and minutes;
o -hh:mm, the time behind UTC in hours and minutes.
If any of the two-digit components of the Datetime value are unknown, 00 should
be used.
LinkTypes
Attribute values of type LinkTypes give a space-separated list of link types. A
link type is case-insensitive and may not contain whitespace. Each link type
may be used any number of times in a given document.
While link types are case-insensitive, the Lynx browser will render LINK
elements with the same case as is given in the REL or REV attribute. Authors
should therefore be consistent in their case, and may wish to capitalize the
first letter while using lowercase for the rest.
The following link types are defined in HTML 4.0, though authors may use other
link types. The Made link type, widely used as <LINK REV=Made
HREF="mailto:liam@htmlhelp.com"> to provide a contact link for the document
author, is notably missing from the list of link types defined in HTML 4.0.
o Alternate specifies an alternate version of the document. When used with the
LINK element's HREFLANG attribute, this value implies a translation of the
document. When used with LINK's MEDIA attribute, a media-specific version
(e.g., for printing) is implied.
o StyleSheet specifies an external style sheet for the document. This link type
can be combined with the Alternate link type to define an alternate style
sheet for the user to choose.
o Start specifies the first document in a collection.
o Next specifies the next document in a suggested sequence of reading. Browsers
such as WebTV will preload documents identified as "next" to improve the
perceived load time.
o Prev specifies the previous document in a suggested sequence of reading.
o Contents specifies a table of contents for the document.
o Index gives an index for the document.
o Glossary gives a glossary of terms used in the document.
o Copyright specifies a document with copyright information.
o Chapter specifies the chapter of a collection of documents.
o Section specifies the section of a collection of documents.
o Subsection specifies a subsection of a collection of documents.
o Appendix gives an appendix for the collection of documents.
o Help specifies a help document.
o Bookmark refers to a key related document. The TITLE attribute provides a
label for the bookmark.
MediaDesc
Attribute values of type MediaDesc are media descriptors--a comma-separated
list of media for which the linked resource is tailored. Media descriptors are
case-sensitive.
The following media descriptors are defined in HTML 4.0:
o screen (the default), for non-paged computer screens;
o tty, for fixed-pitch character grid displays (such as the display used by
Lynx);
o tv, for television-type devices with low resolution and limited
scrollability;
o projection, for projectors;
o handheld, for handheld devices (characterized by a small, monochrome display
and limited bandwidth);
o print, for output to a printer;
o braille, for braille tactile feedback devices;
o aural, for speech synthesizers;
o all, for all devices.
Script
Script attribute values are client-side scripts, typically a function call or a
few short statements. The value may contain entities (e.g., ").
StyleSheet
Attribute values of type StyleSheet are style sheet data. The value may contain
entities.
FrameTarget
Attribute values of type FrameTarget must begin with a letter in the range A-Z
or a-z, with the exception of the following special values that begin with an
underscore:
o _blank renders the link in a new, unnamed window
o _self renders the link in the current frame (useful for overriding a BASE
TARGET)
o _parent renders the link in the immediate FRAMESET parent
o _top renders the link in the full, unframed window
ΓòÉΓòÉΓòÉ 1.3.2.2. HTML 4.0 Common Attributes ΓòÉΓòÉΓòÉ
HTML 4.0 Common Attributes
A number of attributes in HTML 4.0 are common to most elements. These
attributes are divided into core attributes, internationalization attributes,
and scripting events.
Core Attributes
ID
The ID attribute uniquely identifies an element within a document. No two
elements can have the same ID value in a single document. The attribute's value
must begin with a letter in the range A-Z or a-z and may be followed by letters
(A-Za-z), digits (0-9), hyphens ("-"), underscores ("_"), colons (":"), and
periods (".").
The following example uses the ID attribute to identify each of the first two
paragraphs of a document:
<P ID=firstp>My first paragraph.</P>
<P ID=secondp>My second paragaph.</P>
The paragraphs in the example could have style rules associated with them
through their ID attributes. The following Cascading Style Sheet defines unique
colors for the two paragraphs:
P#firstp {
color: navy;
background: transparent
}
P#secondp {
color: black;
background: transparent
}
The paragraphs in the initial example could also be used as a target anchor for
links:
<P>See <A HREF="#firstp">the opening paragraph</A>
for more information.</P>
Note that most browsers do not support the ID attribute for link anchors. For
current browsers, authors should use <A NAME>...</A> within the element instead
of ID.
Since ID and NAME share the same name space, authors cannot use the same value
for an ID attribute and a NAME attribute in the same document. Also note that
while NAME may contain entities, the ID attribute value may not.
CLASS
The CLASS attribute specifies the element to be a member of one or more
classes. Classes allow authors to define specific kinds of a given element. For
example, an author could use <CODE CLASS=Java> when giving Java code and <CODE
CLASS=Perl> when giving Perl code.
Unlike with the ID attribute, any number of elements can share the same class.
An element may also belong to multiple classes; the CLASS attribute value is a
space-separated list of class names.
Note that most current browsers do not support multiple classes. Such browsers
typically ignore a CLASS attribute that specifies multiple classes.
The CLASS attribute is particularly useful when combined with style sheets .
For example, consider the following navigation bar:
<DIV CLASS=navbar>
<P><A HREF="/">Home</A> | <A HREF="./">Index</A> | <A
HREF="/search.html">Search</A></P>
<P><A HREF="/"><IMG SRC="logo.gif" ALT="" TITLE="WDG
Logo"></A></P>
</DIV>
This example's use of the CLASS attribute allows style rules to easily be
added. The following Cascading Style Sheet suggests a presentation for the
preceding example:
.navbar {
margin-top: 2em;
padding-top: 1em;
border-top: solid thin navy
}
.navbar IMG { float: right }
@media print {
.navbar { display: none }
}
STYLE
The STYLE attribute allows authors to specify style rules inline for a single
occurrence of an element. An example follows:
<P>A popular font for on-screen reading is
<SPAN STYLE="font-family: Verdana">Verdana</SPAN>.</P>
When the STYLE attribute is used, a default style sheet language must be
specified for the document by setting the Content-Style-Type HTTP header to the
media type of the style sheet language. The previous example could use the
following META element in the document's HEAD:
<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">
In most cases, use of the CLASS or ID attributes is a better choice than using
STYLE since ID and CLASS can be selectively applied to different media and
since they provide a separation of content and presentation that often
simplifies maintenance.
TITLE
The TITLE attribute provides a title for an element and is commonly implemented
as a "tooltip" on visual browsers, though many browsers lack support for TITLE.
The attribute is most useful with A, LINK, IMG, and OBJECT elements, where it
provides a title for the linked or embedded resource. Some examples follow:
o
<A HREF="mailto:liam@htmlhelp.com"
TITLE="Feedback on HTML 4.0 Reference">
liam@htmlhelp.com</A>
o
<A HREF="http://www-genome.wi.mit.edu/ftp/pub/software/WWW/cgi_docs.html"
TITLE="CGI.pm - a Perl5 CGI Library">CGI.pm</A>
o <LINK REL=Alternate HREF="index.fr.html" HREFLANG=fr LANG=fr
TITLE="Version franЗaise">
o
<OBJECT CLASSID="java:Yahtzee.class"
CODETYPE="application/java" WIDTH=400 HEIGHT=250
STANDBY="Ready to play Yahtzee?" TITLE="My Yahtzee Game">
<IMG SRC="yahtzee.gif" ALT="" TITLE="A Yahtzee animation">
Yahtzee is my <EM>favorite</EM> game!
</OBJECT>
TITLE is also helpful with the ABBR and ACRONYM elements to provide the long
form of the abbreviation. Examples:
o He weighs 180 <ABBR TITLE=pounds>lbs.</ABBR>
o <ABBR TITLE="Parti QuВbВcois" LANG=fr-CA>PQ</ABBR>
o <ACRONYM TITLE="North Atlantic Treaty Organization">NATO</ACRONYM>
Internationalization Attributes
LANG
The LANG attribute specifies the language of an element's attribute values and
its content, including all contained elements that do not specify their own
LANG attribute. While the LANG attribute is not widely supported, its use may
help search engines index a document by its language while allowing speech
synthesizers to use language-dependent pronunciation rules. As well, visual
browsers can use the language's proper quotation marks when rendering the Q
element.
The attribute value is case-insensitive, and should be specified according to
RFC 1766; examples include en for English, en-US for American English, and ja
for Japanese. Whitespace is not allowed in the language code.
Use of the LANG attribute also allows authors to easily change the style of
text depending on the language. For example, a bilingual document may have one
language in italics if rendered visually or a different voice if rendered
aurally. The HTML of such a document might be as follows:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN"
"http://www.w3.org/TR/REC-html40/strict.dtd">
<TITLE>Welcome - Bienvenue</TITLE>
<H1>
<SPAN LANG=en>Welcome</SPAN> -
<SPAN LANG=fr>Bienvenue</SPAN>
</H1>
<P LANG=en>This paragraph is in English.</P>
<P LANG=fr>Ce paragraphe est en franЗais.</P>
...
A document's primary language may be set using the LANG attribute on the HTML
element, or, alternatively, by using the Content-Language HTTP header.
DIR
The DIR attribute specifies the directionality of text--left-to-right (DIR=ltr,
the default) or right-to-left (DIR=rtl). Characters in Unicode are assigned a
directionality, left-to-right or right-to-left, to allow the text to be
rendered properly. For example, while English characters are presented
left-to-right, Hebrew characters are presented right-to-left.
Unicode defines a bidirectional algorithm that must be applied whenever a
document contains right-to-left characters. While this algorithm usually gives
the proper presentation, some situations leave directionally neutral text and
require the DIR attribute to specify the base directionality.
Text is often directionally neutral when there are multiple embeddings of
content with a different directionality. For example, an English sentence that
contains a Hebrew phrase that contains an English quotation would require the
DIR attribute to define the directionality of the Hebrew phrase. The Hebrew
phrase, including the English quotation, should be contained within a SPAN
element with DIR=rtl.
Common Scripting Events
A number of attributes that define client-side scripting events are common to
most elements. The attribute value is a script--typically a function call or a
few short statements--that is executed when the event occurs. The value may
contain entities (e.g., " ).
The following example features JavaScript code to handle two events of a submit
button, giving the user a reminder in the status bar when the mouse moves over
the button and clearing the status bar when the mouse moves away. Note that the
attribute values are delimited by single quotes since double quotes are used
within them.
<INPUT TYPE=submit ONMOUSEOVER='window.status="Did you fill in
all required fields?";' ONMOUSEOUT='window.status="";'>
When an event attribute is used, a default scripting language must be specified
for the document by setting the Content-Script-Type HTTP header to the media
type of the scripting language. The previous example could use the following
META element in the document's HEAD:
<META HTTP-EQUIV="Content-Script-Type" CONTENT="text/javascript">
The common event attributes are device-dependent and largely tailored for the
graphical user interface. The available events are as follows:
o ONCLICK, when the mouse button is clicked on an element;
o ONDBLCLICK, when the mouse button is double-clicked on an element;
o ONMOUSEDOWN, when the mouse button is pressed over an element;
o ONMOUSEUP, when the mouse button is released over an element;
o ONMOUSEOVER, when the mouse is moved onto an element;
o ONMOUSEMOVE, when the mouse is moved while over an element;
o ONMOUSEOUT, when the mouse is moved away from an element;
o ONKEYPRESS, when a key is pressed and released over an element;
o ONKEYDOWN, when a key is pressed down over an element;
o ONKEYUP, when a key is released over an element.
ΓòÉΓòÉΓòÉ 1.3.2.2.1. Core Attributes ΓòÉΓòÉΓòÉ
Core Attributes
ID
The ID attribute uniquely identifies an element within a document. No two
elements can have the same ID value in a single document. The attribute's value
must begin with a letter in the range A-Z or a-z and may be followed by letters
(A-Za-z), digits (0-9), hyphens ("-"), underscores ("_"), colons (":"), and
periods (".").
The following example uses the ID attribute to identify each of the first two
paragraphs of a document:
<P ID=firstp>My first paragraph.</P>
<P ID=secondp>My second paragaph.</P>
The paragraphs in the example could have style rules associated with them
through their ID attributes. The following Cascading Style Sheet defines unique
colors for the two paragraphs:
P#firstp {
color: navy;
background: transparent
}
P#secondp {
color: black;
background: transparent
}
The paragraphs in the initial example could also be used as a target anchor for
links:
<P>See <A HREF="#firstp">the opening paragraph</A>
for more information.</P>
Note that most browsers do not support the ID attribute for link anchors. For
current browsers, authors should use <A NAME>...</A> within the element instead
of ID.
Since ID and NAME share the same name space, authors cannot use the same value
for an ID attribute and a NAME attribute in the same document. Also note that
while NAME may contain entities, the ID attribute value may not.
CLASS
The CLASS attribute specifies the element to be a member of one or more
classes. Classes allow authors to define specific kinds of a given element. For
example, an author could use <CODE CLASS=Java> when giving Java code and <CODE
CLASS=Perl> when giving Perl code.
Unlike with the ID attribute, any number of elements can share the same class.
An element may also belong to multiple classes; the CLASS attribute value is a
space-separated list of class names.
Note that most current browsers do not support multiple classes. Such browsers
typically ignore a CLASS attribute that specifies multiple classes.
The CLASS attribute is particularly useful when combined with style sheets .
For example, consider the following navigation bar:
<DIV CLASS=navbar>
<P><A HREF="/">Home</A> | <A HREF="./">Index</A> | <A
HREF="/search.html">Search</A></P>
<P><A HREF="/"><IMG SRC="logo.gif" ALT="" TITLE="WDG
Logo"></A></P>
</DIV>
This example's use of the CLASS attribute allows style rules to easily be
added. The following Cascading Style Sheet suggests a presentation for the
preceding example:
.navbar {
margin-top: 2em;
padding-top: 1em;
border-top: solid thin navy
}
.navbar IMG { float: right }
@media print {
.navbar { display: none }
}
STYLE
The STYLE attribute allows authors to specify style rules inline for a single
occurrence of an element. An example follows:
<P>A popular font for on-screen reading is
<SPAN STYLE="font-family: Verdana">Verdana</SPAN>.</P>
When the STYLE attribute is used, a default style sheet language must be
specified for the document by setting the Content-Style-Type HTTP header to the
media type of the style sheet language. The previous example could use the
following META element in the document's HEAD:
<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">
In most cases, use of the CLASS or ID attributes is a better choice than using
STYLE since ID and CLASS can be selectively applied to different media and
since they provide a separation of content and presentation that often
simplifies maintenance.
TITLE
The TITLE attribute provides a title for an element and is commonly implemented
as a "tooltip" on visual browsers, though many browsers lack support for TITLE.
The attribute is most useful with A, LINK, IMG, and OBJECT elements, where it
provides a title for the linked or embedded resource. Some examples follow:
o
<A HREF="mailto:liam@htmlhelp.com"
TITLE="Feedback on HTML 4.0 Reference">
liam@htmlhelp.com</A>
o
<A HREF="http://www-genome.wi.mit.edu/ftp/pub/software/WWW/cgi_docs.html"
TITLE="CGI.pm - a Perl5 CGI Library">CGI.pm</A>
o <LINK REL=Alternate HREF="index.fr.html" HREFLANG=fr LANG=fr
TITLE="Version franЗaise">
o
<OBJECT CLASSID="java:Yahtzee.class"
CODETYPE="application/java" WIDTH=400 HEIGHT=250
STANDBY="Ready to play Yahtzee?" TITLE="My Yahtzee Game">
<IMG SRC="yahtzee.gif" ALT="" TITLE="A Yahtzee animation">
Yahtzee is my <EM>favorite</EM> game!
</OBJECT>
TITLE is also helpful with the ABBR and ACRONYM elements to provide the long
form of the abbreviation. Examples:
o He weighs 180 <ABBR TITLE=pounds>lbs.</ABBR>
o <ABBR TITLE="Parti QuВbВcois" LANG=fr-CA>PQ</ABBR>
o <ACRONYM TITLE="North Atlantic Treaty Organization">NATO</ACRONYM>
ΓòÉΓòÉΓòÉ 1.3.2.2.2. Internationalization Attributes ΓòÉΓòÉΓòÉ
Internationalization Attributes
LANG
The LANG attribute specifies the language of an element's attribute values and
its content, including all contained elements that do not specify their own
LANG attribute. While the LANG attribute is not widely supported, its use may
help search engines index a document by its language while allowing speech
synthesizers to use language-dependent pronunciation rules. As well, visual
browsers can use the language's proper quotation marks when rendering the Q
element.
The attribute value is case-insensitive, and should be specified according to
RFC 1766; examples include en for English, en-US for American English, and ja
for Japanese. Whitespace is not allowed in the language code.
Use of the LANG attribute also allows authors to easily change the style of
text depending on the language. For example, a bilingual document may have one
language in italics if rendered visually or a different voice if rendered
aurally. The HTML of such a document might be as follows:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN"
"http://www.w3.org/TR/REC-html40/strict.dtd">
<TITLE>Welcome - Bienvenue</TITLE>
<H1>
<SPAN LANG=en>Welcome</SPAN> -
<SPAN LANG=fr>Bienvenue</SPAN>
</H1>
<P LANG=en>This paragraph is in English.</P>
<P LANG=fr>Ce paragraphe est en franЗais.</P>
...
A document's primary language may be set using the LANG attribute on the HTML
element, or, alternatively, by using the Content-Language HTTP header.
DIR
The DIR attribute specifies the directionality of text--left-to-right (DIR=ltr,
the default) or right-to-left (DIR=rtl). Characters in Unicode are assigned a
directionality, left-to-right or right-to-left, to allow the text to be
rendered properly. For example, while English characters are presented
left-to-right, Hebrew characters are presented right-to-left.
Unicode defines a bidirectional algorithm that must be applied whenever a
document contains right-to-left characters. While this algorithm usually gives
the proper presentation, some situations leave directionally neutral text and
require the DIR attribute to specify the base directionality.
Text is often directionally neutral when there are multiple embeddings of
content with a different directionality. For example, an English sentence that
contains a Hebrew phrase that contains an English quotation would require the
DIR attribute to define the directionality of the Hebrew phrase. The Hebrew
phrase, including the English quotation, should be contained within a SPAN
element with DIR=rtl.
ΓòÉΓòÉΓòÉ 1.3.2.2.3. Common Scripting Events ΓòÉΓòÉΓòÉ
Common Scripting Events
A number of attributes that define client-side scripting events are common to
most elements. The attribute value is a script--typically a function call or a
few short statements--that is executed when the event occurs. The value may
contain entities (e.g., " ).
The following example features JavaScript code to handle two events of a submit
button, giving the user a reminder in the status bar when the mouse moves over
the button and clearing the status bar when the mouse moves away. Note that the
attribute values are delimited by single quotes since double quotes are used
within them.
<INPUT TYPE=submit ONMOUSEOVER='window.status="Did you fill in
all required fields?";' ONMOUSEOUT='window.status="";'>
When an event attribute is used, a default scripting language must be specified
for the document by setting the Content-Script-Type HTTP header to the media
type of the scripting language. The previous example could use the following
META element in the document's HEAD:
<META HTTP-EQUIV="Content-Script-Type" CONTENT="text/javascript">
The common event attributes are device-dependent and largely tailored for the
graphical user interface. The available events are as follows:
o ONCLICK, when the mouse button is clicked on an element;
o ONDBLCLICK, when the mouse button is double-clicked on an element;
o ONMOUSEDOWN, when the mouse button is pressed over an element;
o ONMOUSEUP, when the mouse button is released over an element;
o ONMOUSEOVER, when the mouse is moved onto an element;
o ONMOUSEMOVE, when the mouse is moved while over an element;
o ONMOUSEOUT, when the mouse is moved away from an element;
o ONKEYPRESS, when a key is pressed and released over an element;
o ONKEYDOWN, when a key is pressed down over an element;
o ONKEYUP, when a key is released over an element.
ΓòÉΓòÉΓòÉ 1.3.3. Special Characters ΓòÉΓòÉΓòÉ
Special Characters
Certain characters in HTML are reserved for use as markup and must be escaped
to appear literally. The "<" character may be represented with an entity, <.
Similarly, ">" is escaped as >, and "&" is escaped as &. If an attribute
value contains a double quotation mark and is delimited by double quotation
marks, then the quote should be escaped as ".
Other entities exist for special characters that cannot easily be entered with
some keyboards. For example, the copyright symbol ("Γòò") may be represented with
the entity ©. See the Entities section for a complete list of HTML┬á4.0
entities.
As an alternative to entities, authors may also use numeric character
references. Any character may be represented by a numeric character reference
based on its "code position" in Unicode. For example, one could use © for
the copyright symbol or ا for the Arabic letter ALEF.
ΓòÉΓòÉΓòÉ 1.3.4. Comments ΓòÉΓòÉΓòÉ
Comments
Comments in HTML have a complicated syntax that can be simplified by following
this rule: Begin a comment with "<!--", end it with "-->", and do not use "--"
within the comment.
<!-- An example comment -->
═══ 1.3.5. A Complete HTML 4.0 Document ═══
A Complete HTML 4.0 Document
An HTML 4.0 document begins with a DOCTYPE declaration that declares the
version of HTML to which the document conforms. The HTML element follows and
contains the HEAD and BODY. The HEAD contains information about the document,
such as its title and keywords, while the BODY contains the actual content of
the document, made up of block-level elements and inline elements. A basic
HTML 4.0 document takes on the following form:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN"
"http://www.w3.org/TR/REC-html40/strict.dtd">
<HTML>
<HEAD>
<TITLE>The document title</TITLE>
</HEAD>
<BODY>
<H1>Main heading</H1>
<P>A paragraph.</P>
<P>Another paragraph.</P>
<UL>
<LI>A list item.</LI>
<LI>Another list item.</LI>
</UL>
</BODY>
</HTML>
In a Frameset document, the FRAMESET element replaces the BODY element.
ΓòÉΓòÉΓòÉ 1.3.6. Validating your HTML ΓòÉΓòÉΓòÉ
Validating your HTML
Each HTML document should be validated to check for errors such as missing
quotation marks (<A HREF="oops.html>Oops</A>), misspelled element or attribute
names, and invalid structures. Such errors are not always apparent when viewing
a document in a browser since browsers are designed to recover from an author's
errors. However, different browsers recover in different ways, sometimes
resulting in invisible text on one browser but not on others.
The W3C HTML Validation Service checks the validity of HTML 4.0 documents.
Note that some programs claim to be validators but really are not. A validator
checks a document against a formal document type definition (DTD) while other
programs such as lints warn about valid but unsafe HTML. Both kinds of programs
are useful, but validation should never be forgotten.
ΓòÉΓòÉΓòÉ 1.4. Organizational List of HTML 4.0 Elements ΓòÉΓòÉΓòÉ
HTML 4.0 Elements
The following is an organizational list of all HTML 4.0 elements. An
alphabetical list is also available.
o Top-level Elements
- HTML - HTML document
o HEAD - Document head
o BODY - Document body
o FRAMESET - Frameset
o Head Elements
- BASE - Document base URI
- ISINDEX - Input prompt
- LINK - Document relationship
- META - Metadata
- SCRIPT - Client-side script
- STYLE - Embedded style sheet
- TITLE - Document title
o Generic Block-level Elements
- ADDRESS - Address
- BLOCKQUOTE - Block quotation
- CENTER - Centered block
- DEL - Deleted text
- DIV - Generic block-level container
- H1 - Level-one heading
- H2 - Level-two heading
- H3 - Level-three heading
- H4 - Level-four heading
- H5 - Level-five heading
- H6 - Level-six heading
- INS - Inserted text
- ISINDEX - Input prompt
- NOSCRIPT - Alternate script content
- P - Paragraph
- PRE - Preformatted text
o Lists
- DIR - Directory list
- DL - Definition list
o DT - Definition term
o DD - Definition description
- LI - List item
- MENU - Menu list
- OL - Ordered list
- UL - Unordered list
o Tables
- TABLE - Table
o CAPTION - Table caption
o COLGROUP - Table column group
- COL - Table column
o THEAD - Table head
o TFOOT - Table foot
o TBODY - Table body
o TR - Table row
- TD - Table data cell
- TH - Table header cell
o Forms
- FORM - Interactive form
o BUTTON - Button
o FIELDSET - Form control group
- LEGEND - Fieldset caption
o INPUT - Form input
o LABEL - Form field label
o SELECT - Option selector
- OPTGROUP - Option group
o OPTION - Menu option
o TEXTAREA - Multi-line text input
o Special Inline Elements
- A - Anchor
- APPLET - Java applet
- BASEFONT - Base font change
- BDO - BiDi override
- BR - Line break
- FONT - Font change
- IFRAME - Inline frame
- IMG - Inline image
- MAP - Image map
o AREA - Image map region
- OBJECT - Object
- PARAM - Object parameter
- Q - Short quotation
- SCRIPT - Client-side script
- SPAN - Generic inline container
- SUB - Subscript
- SUP - Superscript
o Phrase Elements
- ABBR - Abbreviation
- ACRONYM - Acronym
- CITE - Citation
- CODE - Computer code
- DEL - Deleted text
- DFN - Defined term
- EM - Emphasis
- INS - Inserted text
- KBD - Text to be input
- SAMP - Sample output
- STRONG - Strong emphasis
- VAR - Variable
o Font Style Elements
- B - Bold text
- BIG - Large text
- I - Italic text
- S - Strike-through text
- SMALL - Small text
- STRIKE - Strike-through text
- TT - Teletype text
- U - Underlined text
o Frames
- FRAMESET - Frameset
o FRAME - Frame
- NOFRAMES - Frames alternate content
ΓòÉΓòÉΓòÉ 1.4.1. HTML 4.0 Top-Level Elements ΓòÉΓòÉΓòÉ
Top-Level Elements
o HTML - HTML document
- HEAD - Document head
- BODY - Document body
- FRAMESET - Frameset
ΓòÉΓòÉΓòÉ 1.4.2. HTML 4.0 Head Elements ΓòÉΓòÉΓòÉ
Head Elements
o BASE - Document base URI
o ISINDEX - Input prompt
o LINK - Document relationship
o META - Metadata
o SCRIPT - Client-side script
o STYLE - Embedded style sheet
o TITLE - Document title
ΓòÉΓòÉΓòÉ 1.4.3. HTML 4.0 Generic Block-level Elements ΓòÉΓòÉΓòÉ
Generic Block-level Elements
o ADDRESS - Address
o BLOCKQUOTE - Block quotation
o CENTER - Centered block
o DEL - Deleted text
o DIV - Generic block-level container
o H1 - Level-one heading
o H2 - Level-two heading
o H3 - Level-three heading
o H4 - Level-four heading
o H5 - Level-five heading
o H6 - Level-six heading
o INS - Inserted text
o ISINDEX - Input prompt
o NOSCRIPT - Alternate script content
o P - Paragraph
o PRE - Preformatted text
ΓòÉΓòÉΓòÉ 1.4.4. HTML 4.0 List Elements ΓòÉΓòÉΓòÉ
List Elements
o DIR - Directory list
o DL - Definition list
- DT - Definition term
- DD - Definition description
o LI - List item
o MENU - Menu list
o OL - Ordered list
o UL - Unordered list
ΓòÉΓòÉΓòÉ 1.4.5. HTML 4.0 Table Elements ΓòÉΓòÉΓòÉ
Table Elements
o TABLE - Table
- CAPTION - Table caption
- COLGROUP - Table column group
o COL - Table column
- THEAD - Table head
- TFOOT - Table foot
- TBODY - Table body
- TR - Table row
o TD - Table data cell
o TH - Table header cell
ΓòÉΓòÉΓòÉ 1.4.6. HTML 4.0 Form Elements ΓòÉΓòÉΓòÉ
Form Elements
o FORM - Interactive form
- BUTTON - Button
- FIELDSET - Form control group
o LEGEND - Fieldset caption
- INPUT - Form input
- LABEL - Form field label
- SELECT - Option selector
o OPTGROUP - Option group
- OPTION - Menu option
- TEXTAREA - Multi-line text input
ΓòÉΓòÉΓòÉ 1.4.7. HTML 4.0 Special Inline Elements ΓòÉΓòÉΓòÉ
Special Inline Elements
o A - Anchor
o APPLET - Java applet
o BASEFONT - Base font change
o BDO - BiDi override
o BR - Line break
o FONT - Font change
o IFRAME - Inline frame
o IMG - Inline image
o MAP - Image map
- AREA - Image map region
o OBJECT - Object
o PARAM - Object parameter
o Q - Short quotation
o SCRIPT - Client-side script
o SPAN - Generic inline container
o SUB - Subscript
o SUP - Superscript
ΓòÉΓòÉΓòÉ 1.4.8. HTML 4.0 Phrase Elements ΓòÉΓòÉΓòÉ
Phrase Elements
o ABBR - Abbreviation
o ACRONYM - Acronym
o CITE - Citation
o CODE - Computer code
o DEL - Deleted text
o DFN - Defined term
o EM - Emphasis
o INS - Inserted text
o KBD - Text to be input
o SAMP - Sample output
o STRONG - Strong emphasis
o VAR - Variable
ΓòÉΓòÉΓòÉ 1.4.9. HTML 4.0 Font Style Elements ΓòÉΓòÉΓòÉ
Font Style Elements
o B - Bold text
o BIG - Large text
o I - Italic text
o S - Strike-through text
o SMALL - Small text
o STRIKE - Strike-through text
o TT - Teletype text
o U - Underlined text
ΓòÉΓòÉΓòÉ 1.4.10. HTML 4.0 Frames ΓòÉΓòÉΓòÉ
Frames
Frames allow an author to display multiple documents in a single window that is
divided into rectangular subspaces called frames. Visual browsers allow these
frames to be scrolled independently of each other, and links can be loaded in a
frame without changing the content of other frames.
The HTML 4.0 frames model has significant flaws that make frames hated by many
users. Frames should only be used with great care; see the Guide to frames
usage for some guidelines on suitable use of frames.
In a Frameset document, the outermost FRAMESET element takes the place of BODY
and immediately follows the HEAD. Contained within the FRAMESET element are
FRAME elements that define each frame, other FRAMESET elements for complex
layouts, and a NOFRAMES element to provide alternate content for browsers with
frames disabled or not supported.
o FRAMESET - Frameset
- FRAME - Frame
o NOFRAMES - Frames alternate content
ΓòÉΓòÉΓòÉ 1.5. Alphabetical List of HTML 4.0 Elements ΓòÉΓòÉΓòÉ
HTML 4.0 Elements
The following is an alphabetical list of all HTML 4.0 elements. An
organizational list is also available.
o A - Anchor
o ABBR - Abbreviation
o ACRONYM - Acronym
o ADDRESS - Address
o APPLET - Java applet
o AREA - Image map region
o B - Bold text
o BASE - Document base URI
o BASEFONT - Base font change
o BDO - BiDi override
o BIG - Large text
o BLOCKQUOTE - Block quotation
o BODY - Document body
o BR - Line break
o BUTTON - Button
o CAPTION - Table caption
o CENTER - Centered block
o CITE - Citation
o CODE - Computer code
o COL - Table column
o COLGROUP - Table column group
o DD - Definition description
o DEL - Deleted text
o DFN - Defined term
o DIR - Directory list
o DIV - Generic block-level container
o DL - Definition list
o DT - Definition term
o EM - Emphasis
o FIELDSET - Form control group
o FONT - Font change
o FORM - Interactive form
o FRAME - Frame
o FRAMESET - Frameset
o H1 - Level-one heading
o H2 - Level-two heading
o H3 - Level-three heading
o H4 - Level-four heading
o H5 - Level-five heading
o H6 - Level-six heading
o HEAD - Document head
o HR - Horizontal rule
o HTML - HTML document
- DOCTYPE
o I - Italic text
o IFRAME - Inline frame
o IMG - Inline image
o INPUT - Form input
o INS - Inserted text
o ISINDEX - Input prompt
o KBD - Text to be input
o LABEL - Form field label
o LEGEND - Fieldset caption
o LI - List item
o LINK - Document relationship
o MAP - Image map
o MENU - Menu list
o META - Metadata
o NOFRAMES - Frames alternate content
o NOSCRIPT - Alternate script content
o OBJECT - Object
o OL - Ordered list
o OPTGROUP - Option group
o OPTION - Menu option
o P - Paragraph
o PARAM - Object parameter
o PRE - Preformatted text
o Q - Short quotation
o S - Strike-through text
o SAMP - Sample output
o SCRIPT - Client-side script
o SELECT - Option selector
o SMALL - Small text
o SPAN - Generic inline container
o STRIKE - Strike-through text
o STRONG - Strong emphasis
o STYLE - Embedded style sheet
o SUB - Subscript
o SUP - Superscript
o TABLE - Table
o TBODY - Table body
o TD - Table data cell
o TEXTAREA - Multi-line text input
o TFOOT - Table foot
o TH - Table header cell
o THEAD - Table head
o TITLE - Document title
o TR - Table row
o TT - Teletype text
o U - Underlined text
o UL - Unordered list
o VAR - Variable
ΓòÉΓòÉΓòÉ 1.5.1. A - Anchor ΓòÉΓòÉΓòÉ
A - Anchor
Syntax
<A>...</A>
Attribute Specifications
o HREF= URI (hypertext reference)
o NAME= CDATA (named link destination)
o REL= LinkTypes (relationship to link)
o REV= LinkTypes (relationship from link)
o TYPE= ContentType (content-type of link)
o TARGET= FrameTarget (frame to render link in)
o HREFLANG= LanguageCode (language of link)
o CHARSET= Charset (character encoding of link)
o ACCESSKEY= Character (shortcut key)
o TABINDEX= Number (position in tabbing order)
o SHAPE=[ rect | circle | poly | default ] (client-side image map)
o COORDS=Coords (client-side image map)
o ONFOCUS= Script (element received focus)
o ONBLUR= Script (element lost focus)
o common attributes
Contents
Inline elements except A
Contained in
Block-level elements, inline elements except A
The A element denotes an anchor--a hypertext link or the destination of a
link. The HREF attribute specifies a hypertext link to another resource, such
as an HTML document or a JPEG image. Examples:
<A HREF="album.html">My photo album</A>
<A HREF="images/me.jpg">Picture of me</A>
<A HREF="/sounds/auldlang.mid" TYPE="audio/midi"
ACCESSKEY=A>Auld Lang Syne (5 kB MIDI)</A>
<A HREF="section2.html" TARGET="content"
TITLE="Elements of the HEAD" REL=next>Section 2</A>
<A HREF="mailto:liam@htmlhelp.com"
TITLE="Feedback on HTML 4.0 Reference">liam@htmlhelp.com</A>
<A HREF="http://www.htmlhelp.com/"
TARGET="_top">Web Design Group</A>
<A
HREF="http://babel.alis.com:8080/langues/iso639.zh.htm"
CHARSET="big5" HREFLANG=zh>ISO 639</A>
The value of the HREF attribute is the URI of the link. The TYPE attribute
can be used to specify the Internet media type of the link, allowing browsers
to avoid fetching a resource that they cannot handle.
The TITLE attribute can be used to briefly describe the contents of the link
and is rendered as a "tooltip" by some visual browsers. With mailto links,
some browsers use the TITLE attribute value as a subject for the e-mail
message.
The content of an A element used as a link should be as context-free as
possible. In other words, a user should be able to pull all A elements from a
document and still have an idea what lies behind each link. Link text that
contains Click here or simply here is extremely bad form.
The TARGET attribute is used with frames to specify in which frame the link
should be rendered. If no frame with such a name exists, the link is rendered
in a new window unless overridden by the user. Special frame names begin with
an underscore:
o _blank renders the link in a new, unnamed window
o _self renders the link in the current frame (useful for overriding a BASE
TARGET)
o _parent renders the link in the immediate FRAMESET parent
o _top renders the link in the full, unframed window
The optional HREFLANG and CHARSET attributes give the language and character
encoding, respectively, of the link. The language should be specified
according to RFC 1766; examples include en for English, en-US for American
English, and ja for Japanese. Examples of character encodings include
ISO-8859-1, SHIFT_JIS, and UTF-8.
The ACCESSKEY attribute specifies a single Unicode character as a shortcut key
for following the link. Entities (e.g. é) may be used as the ACCESSKEY
value.
The TABINDEX attribute specifies a number between 0 and 32767 to indicate the
tabbing order of the element. An anchor with TABINDEX=0 or no TABINDEX
attribute will be visited after any elements with a positive TABINDEX. Among
positive TABINDEX values, the lower number receives focus first. In the case
of a tie, the element appearing first in the HTML document takes precedence.
The REL and REV attributes define relationships between an anchor and the
linked resource. REL defines a link relationship from the current document to
the linked document while REV defines a relationship in the opposite
direction. For example,
<A HREF="foo.html" REL=glossary>...</A>
indicates that foo.html is a glossary for the current document while
<A HREF="bar.html" REV=subsection>...</A>
indicates that the current document is a subsection of bar.html. The value of
the REL and REV attributes is a space-separated list of link types.
The NAME attribute defines a destination for a link. For example, a document
containing
<H1><A NAME=foo>My Heading</A></H1>
defines a link destination named "foo" at the indicated heading. One could
then use HREF="#foo" in an A element within the same document or
HREF="somedoc.html#foo" from within another document.
An A element cannot contain another A element, so one must be careful that
named anchors do not contain link anchors. Authors can use both the NAME and
HREF attributes in a single A element to avoid this problem.
HTML 4.0's ID attribute is intended to eliminate the need for A NAME. The ID
attribute can be used with almost any element to define a link destination, so
that the following could be used in place of the previous example:
<H1 ID=foo>My heading</H1>
However, browser support for ID link destinations is very poor, so A NAME
will be needed for quite awhile.
NAME and ID values must be unique in any document, and different values must
differ by more than just the case. Values must begin with a letter in the
range A-Z or a-z, and may be followed by A-Z, a-z, 0-9, hyphens, underscores,
colons, or periods. When linking to a named anchor, the name is treated as
case sensitive.
The SHAPE and COORDS attributes of A can be used to create client-side image
maps via the OBJECT element. The default SHAPE value is rect, which
defines a rectangular region using COORDS="left, top, right, bottom". Other
SHAPE values are
o default, which specifies the entire image;
o circle, which specifies a circular region using COORDS="center-x, center-y,
radius";
o poly, which specifies a polygonal region using COORDS="x1, y1, x2, y2, ...,
xN, yN".
Coordinate values are relative to the top left corner of the object and may be
expressed as pixels or percentages. A percentage radius value for circular
regions is calculated relative to the smaller of the object's width and height.
If two or more regions overlap, the earliest specified region takes precedence.
In addition to the core events common to most elements, A accepts the
following event attributes for client-side scripting:
o ONFOCUS, when the link receives focus;
o ONBLUR, when the link loses focus.
ΓòÉΓòÉΓòÉ 1.5.2. ABBR - Abbreviation ΓòÉΓòÉΓòÉ
ABBR - Abbreviation
Syntax
<ABBR>...</ABBR>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The ABBR element is used to markup abbreviations. The TITLE attribute is
useful in conjunction with ABBR to give the long form of the abbreviation,
allowing visual browsers to provide the long form as a "tooltip". If the short
form is a pronounceable word, the ACRONYM element should be used instead of
ABBR.
Examples:
<ABBR TITLE="United Nations">U.N.</ABBR>
He weighs 180 <ABBR TITLE=pounds>lbs.</ABBR>
<ABBR TITLE="Parti Quщbщcois" LANG=fr-CA>PQ</ABBR>
<ACRONYM TITLE="North Atlantic Treaty
Organization">NATO</ACRONYM>
Some short forms, such as "SQL" and "URL," are pronounced as words by some but
pronounced letter-by-letter by others. In such cases, the ABBR element should
be favored over ACRONYM. A style sheet could be used to suggest the aural
rendering. For example, one could use
<ABBR TITLE="Uniform Resource Locator">URL</ABBR>
with the following CSS2 style sheet:
abbr[title="Uniform Resource Locator"] { speak: spell-out }
ΓòÉΓòÉΓòÉ 1.5.3. ACRONYM - Acronym ΓòÉΓòÉΓòÉ
Syntax
<ACRONYM>...</ACRONYM>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The ACRONYM element is used to markup acronyms. The TITLE attribute is
useful in conjunction with ACRONYM to give the long form of the acronym,
allowing visual browsers to provide the long form as a "tooltip". Examples:
<ACRONYM TITLE="North Atlantic Treaty
Organization">NATO</ACRONYM>
<ACRONYM TITLE="radio detecting and ranging">radar</ACRONYM>
<ABBR TITLE="Federal Bureau of Investigation">FBI</ABBR>
Unlike other kinds of abbreviations, acronyms are pronounceable words, though
in some cases the pronunciation is strictly a presentation issue. For example,
"SQL" and "URL" are pronounced as words by some people and pronounced
letter-by-letter by others. In such cases, authors should use the ABBR
element, possibly with a style sheet rule specifying the pronunciation for
aural rendering.
ΓòÉΓòÉΓòÉ 1.5.4. ADDRESS - Address ΓòÉΓòÉΓòÉ
ADDRESS - Contact Information
Syntax
<ADDRESS>...</ADDRESS>
Attribute Specifications
o common attributes
Contents
o In HTML 4.0 Strict: inline elements
o In HTML 4.0 Transitional: inline elements, P
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The ADDRESS element provides contact information for a document or part of a
document. Information provided by ADDRESS may include the names of the
document's maintainers, links to the maintainers' Web pages, e-mail addresses
for feedback, postal addresses, phone numbers, and so on. The ADDRESS element
is not appropriate for all postal and e-mail addresses; it should be reserved
for providing such information about the contact people for the document.
The following example, most appropriate at the end of a document, gives contact
information about the maintainer:
<ADDRESS>
Maintained by <A HREF="/%7Eliam/">Liam Quinn</A> <
<A HREF="mailto:liam@htmlhelp.com">liam@htmlhelp.com</A>>
</ADDRESS>
ADDRESS can also be used to provide contact information for a portion of a
document, typically a form. The next example gives users contact information
to use in conjunction with an order form:
<FORM METHOD=post ACTION="/cgi-bin/order.cgi">
<FIELDSET>
<LEGEND ACCESSKEY=C>Credit Card Information<BR></LEGEND>
<P>
<LABEL ACCESSKEY=V>
<INPUT TYPE=radio NAME=card VALUE=visa> Visa
</LABEL>
<LABEL ACCESSKEY=M>
<INPUT TYPE=radio NAME=card VALUE=mc> MasterCard
</LABEL>
<BR>
<LABEL ACCESSKEY=N>
Number: <INPUT TYPE=text NAME=number>
</LABEL>
<LABEL ACCESSKEY=E>
Expiry: <INPUT TYPE=text NAME=expiry>
</LABEL>
</P>
</FIELDSET>
<P>
<INPUT TYPE=submit VALUE="Submit order" ACCESSKEY=S>
</P>
<ADDRESS>
If you have any questions about ordering, contact us at
<A HREF="mailto:orders@htmlhelp.com">orders@htmlhelp.com</A>,
or phone our offices at 555-5555.
</ADDRESS>
</FORM>
ΓòÉΓòÉΓòÉ 1.5.5. APPLET - Java applet ΓòÉΓòÉΓòÉ
APPLET - Java Applet
Syntax
<APPLET>...</APPLET>
Attribute Specifications
o CODE= CDATA (class file)
o CODEBASE= URI (base URI for class files)
o WIDTH= Length (applet width)
o HEIGHT= Length (applet height)
o ARCHIVE= CDATA (archive files)
o OBJECT= CDATA (serialized applet)
o NAME= CDATA (name for inter-applet communication)
o ALT= Text (alternate text)
o ALIGN=[ top | middle | bottom | left | right ] (applet alignment)
o HSPACE= Pixels (horizontal gutter)
o VSPACE= Pixels (vertical gutter)
o common attributes
Contents
PARAM elements followed by block-level elements and/or inline
elements
Contained in
Inline elements, block-level elements except PRE
The APPLET element is used to embed Java applets. It has been deprecated in
HTML 4.0 in favor of the more generalized OBJECT element. However, since the
few browsers that support OBJECT do so with significant bugs, APPLET is
currently a more reliable method of embedding Java applets.
APPLET's CODE attribute specifies the name of the class file that contains the
compiled Applet subclass. The value is relative to the URI specified in the
CODEBASE attribute, or to the HTML document's base URI if the CODEBASE
attribute is not given.
The required WIDTH and HEIGHT attributes define the dimensions of the applet.
The value may be given in pixels or as a percentage of the parent element's
width or height.
The ALT attribute can be used to give alternate text for browsers that
recognize the APPLET element but do not support Java or do not have Java
enabled. Authors can also give alternate content between the start and end
tags of the APPLET element--a better method than using the ALT attribute
since it allows authors to include HTML markup in the alternate content and
also works with pre- HTML 3.2 browsers that do not support APPLET.
An APPLET may contain PARAM elements to define applet-specific parameters.
PARAM elements should be specified before any other content of the APPLET
element. In the following example, a decorative Java applet takes two
parameters. The APPLET contains an animated GIF as an alternative for non-Java
browsers.
<APPLET CODE="Animate.class" WIDTH=100 HEIGHT=100>
<PARAM NAME=img1 VALUE="/images/1.jpg">
<PARAM NAME=img2 VALUE="/images/2.jpg">
<IMG SRC="animation.gif" ALT="" WIDTH=100 HEIGHT=100>
</APPLET>
The ARCHIVE attribute can specify a comma-separated list of archived files
(either absolute URIs or URIs relative to the CODEBASE), allowing the browser
to download many files with a single connection and hence decreasing the total
download time. The standard archive format for Java files is JAR. JAR files
can be created with the jar tool included with the Java Development Kit 1.1
and up.
Note that some browsers do not support the ARCHIVE attribute, so all necessary
files should be available unarchived as well. Other browsers only support a
single URI as the ARCHIVE value.
The OBJECT attribute specifies a serialized (saved) representation of an
applet. The CODE attribute should not be used if and only if the OBJECT
attribute is specified. When the applet is deserialized, its init() method is
not invoked, but its start() method is. Sun recommends restraint in using
this poorly supported feature.
The ALIGN attribute specifies the alignment of the applet. The values top,
middle, and bottom specify the applet's position with respect to surrounding
content on its left and right.
ALIGN=middle aligns the center of the applet with the current baseline. To
center the applet horizontally on the page, place the applet in a centered
block, e.g.,
<P ALIGN=center><APPLET CODE="Game.class" WIDTH=300
HEIGHT=100></APPLET></P>
The other ALIGN values, left and right, specify a floating applet; the
applet is placed at the left or right margin and content flows around it. To
place content below the applet, use <BR CLEAR=left|right|all> as appropriate.
The vertical-align and float properties of Cascading Style Sheets provide
more flexible methods of aligning applets.
The HSPACE and VSPACE attributes allow an author to suggest horizontal
gutters and vertical gutters, respectively, around the applet. The value must
be in pixels and applies to both sides of the applet. Style sheets provide
more flexibility in specifying the space around applets.
ΓòÉΓòÉΓòÉ 1.5.6. AREA - Image map region ΓòÉΓòÉΓòÉ
AREA - Image Map Region
Syntax
<AREA>
Attribute Specifications
o SHAPE=[ rect | circle | poly | default ] (shape of region)
o COORDS=Coords (coordinates of region)
o HREF= URI (linked resource)
o TARGET= FrameTarget (frame to render link in)
o NOHREF (inactive region)
o ALT= Text (alternate text)
o TABINDEX= Number (position in tabbing order)
o ONFOCUS= Script (region received focus)
o ONBLUR= Script (region lost focus)
o common attributes
Contents
Empty
Contained in
MAP
The AREA element defines a map region in a client-side image map. Each map
region is a piece of the image with a different action when clicked.
The SHAPE and COORDS attributes of AREA specify what part of the image is
included in the region. The default SHAPE value is rect, which defines a
rectangular region using COORDS="left, top, right, bottom". Other SHAPE
values are
o default, which specifies the entire image;
o circle, which specifies a circular region using COORDS="center-x, center-y,
radius";
o poly, which specifies a polygonal region using COORDS="x1, y1, x2, y2, ...,
xN, yN".
Coordinate values are relative to the top left corner of the object and may be
expressed as pixels or percentages. A percentage radius value for circular
regions is calculated relative to the smaller of the object's width and height.
If two or more regions overlap, the earliest specified region takes precedence.
The HREF attribute specifies a link to another resource, such as an HTML
document or a JPEG image. The TITLE attribute can be used to briefly
describe the contents of the link and is rendered as a "tooltip" by some visual
browsers. The boolean NOHREF attribute indicates that the region has no link.
The required ALT attribute provides alternate text for those not loading
images. Effective ALT text should generally give the function of the map
region rather than a description of the region. For example, ALT="WDG Home"
or ALT="Web Design Group" would be more appropriate than ALT="WDG Logo" for a
map region whose link went to the WDG home page. Good ALT text is crucial to
the document's accessibility for the significant portion of users who do not
load images.
The TARGET attribute is used with frames to specify in which frame the link
should be rendered. If no frame with such a name exists, the link is rendered
in a new window unless overridden by the user. Special frame names begin with
an underscore:
o _blank renders the link in a new, unnamed window
o _self renders the link in the current frame (useful for overriding a BASE
TARGET)
o _parent renders the link in the immediate FRAMESET parent
o _top renders the link in the full, unframed window
The ACCESSKEY attribute specifies a single Unicode character as a shortcut key
for following the link. Entities (e.g. é) may be used as the ACCESSKEY
value.
The TABINDEX attribute specifies a number between 0 and 32767 to indicate the
tabbing order of the map region. A region with TABINDEX=0 or no TABINDEX
attribute will be visited after any elements with a positive TABINDEX. Among
positive TABINDEX values, the lower number receives focus first. In the case
of a tie, the element appearing first in the HTML document takes precedence.
In addition to the core events common to most elements, AREA accepts the
following event attributes for client-side scripting:
o ONFOCUS, when the region receives focus;
o ONBLUR, when the region loses focus.
ΓòÉΓòÉΓòÉ 1.5.7. B - Bold Text ΓòÉΓòÉΓòÉ
B - Bold Text
Syntax
<B>...</B>
Attribute Specifications
common attributes"
Contents
Inline elements
Contained in
Inline elements, block-level elements
The B element suggests that text be rendered as bold text. In most cases, use
of a phrase element such as STRONG is more appropriate since such elements
express the meaning of the text more clearly.
The B element is a suitable choice for marking a structure for which no phrase
element exists. For example, vectors in mathematics have no structural element
in HTML 4.0, but bold text is often an appropriate visual rendering:
If two vectors <B CLASS=vector>v</B> and
<B CLASS=vector>w</B> are orthogonal, we write
<B CLASS=vector>v</B>┬á⊥┬á<B CLASS=vector>w</B>.
Note the use of the CLASS attribute to add structural significance to the B
elements. This allows greater flexibility when applying style sheets to
different kinds of bold text.
ΓòÉΓòÉΓòÉ 1.5.8. BASE - Document base URI ΓòÉΓòÉΓòÉ
BASE - Document Base URI
Syntax
<BASE>
Attribute Specifications
o HREF= URI (base URI reference)
o TARGET= FrameTarget (frame to render links in)
Contents
Empty
Contained in
HEAD
The BASE element defines the document's base URI for resolving relative URIs
contained within the document. A document cannot contain more than one BASE
element. When present, the BASE element must appear in the HEAD, prior to any
elements that include a partial URI.
BASE's HREF attribute, required in HTML 4.0 Strict, specifies the absolute URI
used to resolve relative URIs. See Using Relative URLs for more details on
using and resolving relative URIs.
Most Web pages do not require an explicit base URI since the document's URI
is a suitable base. An explicit base URI is only required when the same
document may be accessed at different URIs or when the document has no URI
(e.g., sending an HTML document by e-mail).
The TARGET attribute is used with frames to specify in which frame all links
in document should be rendered by default. The target frame specified by BASE
can be overridden by a given link using the link's TARGET attribute.
If no frame with the specified target name exists, the links are rendered in a
new window unless overridden by the user. Special frame names begin with an
underscore:
o _blank renders the links in a new, unnamed window
o _self renders the links in the current frame
o _parent renders the links in the immediate FRAMESET parent
o _top renders the links in the full, unframed window
ΓòÉΓòÉΓòÉ 1.5.9. BASEFONT - Base font change ΓòÉΓòÉΓòÉ
BASEFONT - Base Font Change
Syntax
<BASEFONT>
Attribute Specifications
o SIZE= CDATA (font size adjustment)
o COLOR= Color (font color adjustment)
o FACE= CDATA (font face adjustment)
o ID= ID (unique ID)
Contents
Empty
Contained in
Inline elements, block-level elements except PRE
The BASEFONT element, deprecated in HTML 4.0 in favor of style sheets, allows
authors to suggest rudimentary font changes. Use of the BASEFONT element
brings the same usability and accessibility problems as FONT, as discussed in
the article What's Wrong With FONT?
Unlike FONT, BASEFONT's changes affect the base font, and so apply to all
content following the BASEFONT element except for headings. However, most
browsers fail to apply changes in the base font size and color to TABLEs.
BASEFONT's required SIZE attribute specifies the font size to use on a
browser-dependent scale of 1 to 7, with the default being 3.
The poorly supported COLOR and FACE attributes suggest a font color and face,
respectively. Style sheets are better supported and more flexible than
BASEFONT's COLOR and FACE attributes.
ΓòÉΓòÉΓòÉ 1.5.10. BDO - BiDi override ΓòÉΓòÉΓòÉ
BDO - BiDi Override
Syntax
<BDO>...</BDO>
Attribute Specifications
o DIR=[ ltr | rtl ] (directionality of text)
o LANG= LanguageCode (language of text)
o core attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The BDO element overrides the bidirectional algorithm for the enclosed text.
Characters in Unicode are assigned a directionality, left-to-right or
right-to-left, to allow the text to be rendered properly. For example, while
English characters are presented left-to-right, Hebrew characters are presented
right-to-left.
Unicode defines a bidirectional algorithm that must be applied whenever a
document contains right-to-left characters. While this algorithm usually gives
the proper presentation, occasionally authors must override the bidirectional
algorithm and specify the directionality of the text. One such case is when
Hebrew characters are stored in visual order, where the first character of a
word is after the second character. Unicode assumes that the characters are
stored in logical order, where the first character of a word is before the
second character, so the bidirectional algorithm would result in a rendering
with the first character incorrectly to the left of the second character.
The BDO element requires the DIR attribute to specify the directionality of
the enclosed text. If a document contains Hebrew characters stored in visual
order, one should use <BDO DIR=ltr>text</BDO> to force the proper presentation
for that text.
Authors may alternatively override the bidirectional algorithm using the
Unicode character to force left-to-right directionality or
to force right-to-left directionality. The character ends the
overriding of the algorithm. These characters should not be used in combination
with the DIR attribute.
ΓòÉΓòÉΓòÉ 1.5.11. BIG - Large text ΓòÉΓòÉΓòÉ
BIG - Large Font
Syntax
<BIG>...</BIG>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements except PRE
The BIG element suggests that text be rendered in a larger font. In most cases,
use of a structural element such as STRONG or a heading (e.g., H3) is more
appropriate since these elements express the meaning of the text more clearly.
One can suggest that STRONG text be rendered in a larger font with the
following Cascading Style Sheet:
STRONG { font-size: larger }
Most browsers support nested BIG elements, but authors should be wary of making
significant changes to the font size. Different users have different font
sizes, eyesight, and window sizes. Large changes in font size may look right to
the author but ridiculous to some users.
ΓòÉΓòÉΓòÉ 1.5.12. BLOCKQUOTE - Block quotation ΓòÉΓòÉΓòÉ
BLOCKQUOTE - Block Quotation
Syntax
<BLOCKQUOTE>...</BLOCKQUOTE>
Attribute Specifications
o CITE= URI (source of quotation)
o common attributes
Contents
o In HTML 4.0 Strict: one or more block-level elements or SCRIPT
o In HTML 4.0 Transitional: inline elements or block-level elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The BLOCKQUOTE element defines a block quotation. Unlike inline quotations,
block quotations may contain block-level elements such as P and TABLE, but
BLOCKQUOTE may not be contained within a paragraph or inline element.
The optional CITE attribute of BLOCKQUOTE provides the URI of the source of
the quotation. This attribute, not widely supported among browsers, allows
readers to verify the authenticity of the quotation and also find related
information.
The content of the BLOCKQUOTE element should be contained within other
block-level elements, typically P. The following example features a quotation
that includes multiple paragraphs and its own block quotation:
<BLOCKQUOTE
CITE="http://www.bibliomania.com/Fiction/joyce/ulysses/telemac.html">
<P>
He pointed his finger in friendly jest and went over to the parapet, laughing
to himself. Stephen Dedalus stepped up, followed him wearily half way and
sat down on the edge of the gunrest, watching him still as he propped his mirror
on the parapet, dipped the brush in the bowl and lathered cheeks and
neck.</P> <P>Buck Mulligan's gay voice went on.
</P>
<BLOCKQUOTE>
<P>
My name is absurd too: Malachi Mulligan, two dactyls.
But it has a Hellenic ring, hasn't it? Tripping and sunny like the buck
himself. We must go to Athens. Will you come if I can get the aunt to
fork out twenty quid?
</P>
</BLOCKQUOTE>
</BLOCKQUOTE>
Authors should not use BLOCKQUOTE for unquoted material just to achieve a
block indentation in common visual browsers. With the rise of style sheets,
such misuse of BLOCKQUOTE will become less reliable while also reducing the
author's ability to fully exploit the power of style sheets. Cascading Style
Sheets provide the margin-left property to indent a block.
ΓòÉΓòÉΓòÉ 1.5.13. BODY - Document body ΓòÉΓòÉΓòÉ
BODY - Document Body
Syntax
<BODY>...</BODY>
Attribute Specifications
o BACKGROUND= URI (background image for document)
o BGCOLOR= Color (background color for document)
o TEXT= Color (text color for document)
o LINK= Color (link color for document)
o VLINK= Color (visited link color for document)
o ALINK= Color (active link color for document)
o ONLOAD= Script (document has been loaded)
o ONUNLOAD= Script (document has been exited)
o common attributes
Contents
o In HTML 4.0 Strict: one or more block-level elements or SCRIPT, INS, DEL
o In HTML 4.0 Transitional: inline elements, block-level elements, INS, DEL
Contained in
o In HTML 4.0 Strict or Transitional: HTML
o In HTML 4.0 Frameset: NOFRAMES
The BODY element contains the document body. BODY is required in non-frames
documents, but its start and end tags are always optional. In frames
documents, BODY must be contained within the NOFRAMES element, if NOFRAMES
is used.
The BODY element contains the document's content. The content should be
contained within block-level elements or SCRIPT elements, though HTML 4.0
Transitional also allows inline elements directly within BODY.
BODY takes a number of attributes for specifying the background and colors of
the document on visual browsers. These attributes are deprecated in HTML 4.0
in favor of style sheets, which provide greater flexibility in suggesting the
presentation of a document. BGCOLOR suggests a background color, TEXT
suggests a text color, LINK suggests a link color, VLINK suggests a visited
link color, and ACTIVE suggests an active link color (when the link is
selected). If one of these attributes is given, then all of them should be
included to ensure that the user's chosen colors do not interfere with those
suggested in the <BODY> tag. Authors should not rely on the specified colors
being used since browsers allow these colors to be overridden by the user.
The BACKGROUND attribute suggests a background image for tiling on the
document canvas. To help ensure a readable document, the BGCOLOR, TEXT, LINK,
VLINK, and ALINK attributes should always be included when BACKGROUND is
given. The BGCOLOR will be used for those not loading images.
Style sheets allow more flexibility in suggesting a background image,
including the ability to specify the position of the image, how the image is
tiled, and whether the image should scroll with the document.
In addition to the core events common to most elements, BODY accepts the
following event attributes for client-side scripting:
o ONLOAD, when the document has been loaded;
o ONUNLOAD, when the document is exited.
ΓòÉΓòÉΓòÉ 1.5.14. BR - Line break ΓòÉΓòÉΓòÉ
BR - Line Break
Syntax
<BR>
Attribute Specifications
o CLEAR=[ left | all | right | none ] (clear floating objects)
o core attributes
Contents
Empty
Contained in
Inline elements, block-level elements
The BR element forces a break in the current line of text. BR can be useful
in formatting addresses within the ADDRESS element, but it is often misused
to break lines of text in a paragraph or table cell when it looks "nice" to the
author. This usually results in an awkward presentation when viewed with a
font size other than that used by the author.
The CLEAR attribute of BR is used to move below floating objects (typically
images or tables). In the following example, the second paragraph should be
rendered below the floating image:
<P>
<IMG SRC="toronto.jpg" ALIGN=left ALT="" TITLE="Toronto's CN Tower">
Toronto is the largest city in Canada and the fourth largest in North
America.
</P>
<BR CLEAR=left>
<P>The city is highly multicultural, with over 80 ethnic
communities from Africa, Asia, and Europe...
Style sheets provide more flexibility in controlling text flow around objects
and eliminate the need to use BR for this purpose since CSS1's clear property
can be applied to any element (such as the second paragraph in the preceding
example).
ΓòÉΓòÉΓòÉ 1.5.15. BUTTON - Button ΓòÉΓòÉΓòÉ
BUTTON - Button
Syntax
<BUTTON>...</BUTTON>
Attribute Specifications
o NAME= CDATA (key in submitted form)
o VALUE= CDATA (value in submitted form)
o TYPE=[ submit | reset | button ] (type of button)
o DISABLED (disable button)
o ACCESSKEY= Character (shortcut key)
o TABINDEX= Number (position in tabbing order)
o ONFOCUS= Script (element received focus)
o ONBLUR= Script (element lost focus)
o common attributes
Contents
o Inline elements except A, INPUT, SELECT, TEXTAREA, LABEL, BUTTON, and
IFRAME
o Block-level elements except FORM, ISINDEX, and FIELDSET
Contained in
Block-level elements, inline elements except BUTTON
The BUTTON element defines a submit button, reset button, or push button.
Authors can also use INPUT to specify these buttons, but the BUTTON element
allows richer labels, including images and emphasis. However, BUTTON is new
in HTML 4.0 and poorly supported among current browsers, so INPUT is a more
reliable choice at this time.
The TYPE attribute of BUTTON specifies the kind of button and takes the value
submit (the default), reset, or button. The NAME and VALUE attributes
determine the name/value pair sent to the server when a submit button is
pushed. These attributes allow authors to provide multiple submit buttons and
have the form handler take a different action depending on the submit button
used.
Some examples of BUTTON follow:
<BUTTON NAME=submit VALUE=modify ACCESSKEY=M>
Modify information
</BUTTON>
<BUTTON NAME=submit VALUE=continue ACCESSKEY=C>
Continue with application
</BUTTON>
<BUTTON ACCESSKEY=S>
Submit <IMG SRC="checkmark.gif" ALT="✔">
</BUTTON>
<BUTTON TYPE=reset ACCESSKEY=R>Reset
<IMG SRC="x.gif" ALT="✘">
</BUTTON>
<BUTTON TYPE=button ID=toggler ONCLICK="toggle()" ACCESSKEY=H>
Hide <strong>non-strict</strong> attributes
</BUTTON>
The ACCESSKEY attribute, used throughout the preceding examples, specifies a
single Unicode character as a shortcut key for pressing the button. Entities
(e.g. é) may be used as the ACCESSKEY value.
The boolean DISABLED attribute makes the BUTTON element unavailable. The user
is unable to push the button, the button cannot receive focus, and the button
is skipped when navigating the document by tabbing.
The TABINDEX attribute specifies a number between 0 and 32767 to indicate the
tabbing order of the button. A BUTTON element with TABINDEX=0 or no TABINDEX
attribute will be visited after any elements with a positive TABINDEX. Among
positive TABINDEX values, the lower number receives focus first. In the case
of a tie, the element appearing first in the HTML document takes precedence.
The BUTTON element also takes a number of attributes to specify client-side
scripting actions for various events. In addition to the core events common
to most elements, BUTTON accepts the following event attributes:
o ONFOCUS, when the element receives focus;
o ONBLUR, when the element loses focus.
ΓòÉΓòÉΓòÉ 1.5.16. CAPTION - Table caption ΓòÉΓòÉΓòÉ
CAPTION - Table Caption
Syntax
<CAPTION>...</CAPTION>
Attribute Specifications
o ALIGN=[ top | bottom | left | right ] (caption alignment)
o common attributes
Contents
Inline elements
Contained in
TABLE
The CAPTION element defines a table caption. When used, CAPTION must be the
first element in the TABLE. Only inline elements (e.g., STRONG) may be used
within CAPTION.
A good caption should provide a short heading for the table. For simple
tables, the caption can also act as an adequate summary, but for more complex
tables, authors should supplement the CAPTION with a full summary, either
through TABLE's SUMMARY attribute or within a paragraph outside of the
TABLE. The following example features a simple table where the CAPTION
provides a heading and an adequate table summary:
<TABLE>
<CAPTION>Common Usenet Abbreviations</CAPTION>
<THEAD>
<TR>
<TH>Abbreviation</TH>
<TH>Long Form</TH>
</TR>
</THEAD>
<TBODY>
<TR>
<TD>AFAIK</TD>
<TD>As Far As I Know</TD>
</TR>
<TR>
<TD>IMHO</TD>
<TD>In My Humble Opinion</TD>
</TR>
<TR>
<TD>OTOH</TD>
<TD>On The Other Hand</TD>
</TR>
</TBODY>
</TABLE>
The next example uses TABLE's SUMMARY attribute to complement the CAPTION:
<TABLE SUMMARY="This table gives the character entity reference,
decimal character reference, and hexadecimal character
reference for symbols and Greek letters.">
<CAPTION>Symbols and Greek Letters in HTML 4.0</CAPTION>
<COLGROUP>
<COLGROUP SPAN=3>
<THEAD>
<TR>
<TH SCOPE=col>Character</TH>
<TH SCOPE=col>Entity</TH>
<TH SCOPE=col>Decimal</TH>
<TH SCOPE=col>Hex</TH>
</TR>
</THEAD>
<TBODY>
<TR>
<TD SCOPE=row>Latin small f with hook</TD>
<TD>ƒ</TD>
<TD>ƒ</TD>
<TD>ƒ</TD>
</TR>
...
</TBODY>
</TABLE>
The deprecated ALIGN attribute of CAPTION specifies the alignment of the
caption relative to the table. Possible values are top (the default), bottom,
left, and right.
ΓòÉΓòÉΓòÉ 1.5.17. CENTER - Centered block ΓòÉΓòÉΓòÉ
CENTER - Centered Block
Syntax
<CENTER>...</CENTER>
Attribute Specifications
o common attributes
Contents
Inline elements, block-level elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The CENTER element defines a block whose contents are centered horizontally
on visual browsers. <CENTER> is a shorthand for < DIV ALIGN=center>, though
CENTER is slightly better supported among browsers. Both methods of centering
are deprecated in favor of style sheets.
CENTER is still useful for centering tables since many browsers lack support
for <TABLE ALIGN=center> as well as the method of centering tables with
Cascading Style Sheets (setting margin-left and margin-right to auto). An
example follows:
<CENTER>
<TABLE>
<TR ALIGN=center>
<TH SCOPE=col>Name</TH>
<TH SCOPE=col>Age</TH>
<TH SCOPE=col>Country</TH>
</TR>
<TR ALIGN=center>
<TD>Liam Quinn</TD>
<TD>20</TD>
<TD>Canada</TD>
</TR>
</TABLE>
</CENTER>
Note that CENTER only centers the table as a whole, not the contents of each
table cell. The preceding example uses the ALIGN attribute of TR to center
the contents of each cell. The text-align property of Cascading Style Sheets
provides greater flexibility in suggesting horizontal alignment.
ΓòÉΓòÉΓòÉ 1.5.18. CITE - Citation ΓòÉΓòÉΓòÉ
CITE - Citation
Syntax
<CITE>...</CITE>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The CITE element is used to markup citations, such as titles of magazines or
newspapers, ship names, references to other sources, and quotation
attributions. Visual browsers typically render CITE as italic text, but
authors can suggest a rendering using style sheets. Since CITE is a
structural element, it carries meaning, making it preferable to font style
elements such as I when marking up citations.
Example:
<CITE>The Toronto Star</CITE> gave its review of the movie
<CITE>Titanic</CITE> yesterday.
ΓòÉΓòÉΓòÉ 1.5.19. CODE - Computer code ΓòÉΓòÉΓòÉ
CODE - Computer Code
Syntax
<CODE>...</CODE>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The CODE element denotes computer code. Visual browsers typically render CODE
as monospaced text, but authors can suggest a rendering using style sheets.
Since CODE is a structural element, it carries meaning, making it preferable
to font style elements such as TT when marking up computer code.
Since spacing is often important when presenting computer code, the PRE
element can be useful as a container for CODE elements. When used within
other containers, a CODE element has multiple spaces collapsed. The following
example uses CODE within PRE:
<PRE><CODE>
class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello World!");
}
} </CODE></PRE>
ΓòÉΓòÉΓòÉ 1.5.20. COL - Table column ΓòÉΓòÉΓòÉ
COL - Table Column
Syntax
<COL>
Attribute Specifications
o SPAN= Number (number of columns)
o WIDTH= MultiLength (width of each column)
o ALIGN=[ left | center | right | justify | char ] (horizontal alignment of
cells)
o CHAR= Character (alignment character for cells)
o CHAROFF= Length (alignment character offset)
o VALIGN=[ top | middle | bottom | baseline ] (vertical alignment of cells)
o common attributes
Contents
Empty
Contained in
COLGROUP, TABLE
The COL element defines attributes common to a table column. If used, COL
must be after the optional CAPTION and before the optional THEAD in the
TABLE. Unlike COLGROUP, COL does not group columns structurally; it merely
defines attributes common to all cells in one or more columns.
COL's SPAN attribute defines the number of columns that will share the COL
element's other attributes; the default value is 1. COL may be contained
directly in the TABLE element or it may be contained within a COLGROUP. If
COL is in a COLGROUP, the COL's attributes override those of the COLGROUP for
the columns spanned by COL.
The next example uses COL elements within COLGROUPs to assign a different
CLASS to each column:
<TABLE SUMMARY="This table gives the character entity reference,
decimal character reference, and hexadecimal character
reference for 8-bit Latin-1 characters, as well as the
rendering of each in your browser.">
<COLGROUP CLASS="character-description">
<COLGROUP>
<COL CLASS=entity>
<COL SPAN=2 CLASS=numeric>
<COLGROUP>
<COL CLASS="entity-rendering">
<COL CLASS="decimal-rendering">
<COL CLASS="hex-rendering">
<THEAD>
<TR>
<TH SCOPE=col ROWSPAN=2>Character</TH> <TH SCOPE=col ROWSPAN=2>Entity</TH>
<TH SCOPE=col ROWSPAN=2>Decimal</TH>
<TH SCOPE=col ROWSPAN=2>Hex</TH>
<TH SCOPE=colgroup COLSPAN=3>Rendering in Your Browser</TH>
</TR>
<TR>
<TH SCOPE=col>Entity</TH>
<TH SCOPE=col>Decimal</TH>
<TH SCOPE=col>Hex</TH>
</TR>
</THEAD>
<TBODY>
<TR>
<TD SCOPE=row>non-breaking space</TD>
<TD> </TD>
<TD> </TD>
<TD> </TD>
<TD> </TD>
<TD> </TD>
<TD> </TD>
</TR>
...
</TBODY>
</TABLE>
COL also takes a number of presentational attributes, many of which cannot be
completely replaced by style sheets. Since few browsers support COL, authors
may wish to specify these attributes on the TD or TH elements instead.
The WIDTH attribute specifies a width for each column spanned by COL. The
value must be a number in pixels, a percentage of the table width, or a
relative length expressed as i* where i is an integer. A column with
WIDTH="3*" will be allotted three times the width of a column with WIDTH="1*".
The value 0* is equivalent to the minimum width necessary for the column's
contents.
The ALIGN attribute specifies the horizontal alignment for each cell in the
spanned columns. Possible values are left, center, right, justify, and char.
ALIGN=char aligns a cell's contents on the character given in the CHAR
attribute. The default value for the CHAR attribute is the decimal point of
the current language--a period in English. The CHAROFF attribute specifies
the offset to the first occurrence of the alignment character. The attribute's
value is a number in pixels or a percentage of the cell's width; CHAROFF="50%"
centers the alignment character horizontally in a cell.
The VALIGN attribute specifies the vertical position of a cell's contents.
Possible values are:
o top, which positions data at the top of the cell;
o middle, the default value, which centers the cell data vertically;
o bottom, which positions data at the bottom of the cell;
o baseline, which specifies that the first line of each cell in the row with
ALIGN=baseline should occur on a common baseline.
ΓòÉΓòÉΓòÉ 1.5.21. COLGROUP - Table column group ΓòÉΓòÉΓòÉ
COLGROUP - Table Column Group
Syntax
<COLGROUP>...</COLGROUP>
Attribute Specifications
o SPAN= Number (number of columns in group)
o WIDTH= MultiLength (width of each column)
o ALIGN=[ left | center | right | justify | char ] (horizontal alignment of
cells in group)
o CHAR= Character (alignment character for cells)
o CHAROFF= Length (alignment character offset)
o VALIGN=[ top | middle | bottom | baseline ] (vertical alignment of cells
in group)
o common attributes
Contents
Zero or more COL elements
Contained in
TABLE
The COLGROUP element defines a column group in a table. If used, COLGROUP
must be after the optional CAPTION and before the optional THEAD in the
TABLE. The structural divisions defined by COLGROUP allow authors to easily
suggest a presentation for groups of columns through style sheets.
COLGROUP's SPAN attribute defines the number of columns in the group; the
default value is 1. A number of other attributes are permitted on COLGROUP,
and these are shared among the cells of the group. COLGROUP may contain COL
elements that define attributes for the cells of individual columns, overriding
attributes defined for the column group. The SPAN attribute should not be
used if the COLGROUP contains any COL elements.
The next example features three column groups to structurally divide the table
into three parts. The first part is a single column that gives the description
of a character. The second part consists of three columns giving different
ways of representing the character in HTML. The third part consists of three
columns with renderings of the character in the user's browser.
<TABLE SUMMARY="This table gives the character entity reference,
decimal character reference, and hexadecimal character
reference for 8-bit Latin-1 characters, as well as the
rendering of each in your browser.">
<COLGROUP>
<COLGROUP SPAN=3>
<COLGROUP SPAN=3>
<THEAD>
<TR>
<TH SCOPE=col ROWSPAN=2>Character</TH>
<TH SCOPE=col ROWSPAN=2>Entity</TH>
<TH SCOPE=col ROWSPAN=2>Decimal</TH> <TH SCOPE=col ROWSPAN=2>Hex</TH>
<TH SCOPE=colgroup COLSPAN=3>Rendering in Your Browser</TH>
</TR>
<TR>
<TH SCOPE=col>Entity</TH>
<TH SCOPE=col>Decimal</TH>
<TH SCOPE=col>Hex</TH>
</TR>
</THEAD>
<TBODY>
<TR>
<TD SCOPE=row>non-breaking space</TD>
<TD> </TD>
<TD> </TD>
<TD> </TD>
<TD> </TD>
<TD> </TD>
<TD> </TD>
</TR>
...
</TBODY>
</TABLE>
In place of the <COLGROUP SPAN=3> tag in the preceding example, a COLGROUP
with three COL elements could have been used:
<COLGROUP>
<COL CLASS=entity>
<COL CLASS=decimal>
<COL CLASS=hex>
</COLGROUP>
Here we have used the CLASS attribute to distinguish the individual columns
of the group, allowing us to easily suggest different presentations for the
columns through style sheets.
COLGROUP also takes a number of presentational attributes, many of which
cannot be completely replaced by style sheets. Since few browsers support
COLGROUP, authors may wish to specify these attributes on the TD or TH
elements instead.
The WIDTH attribute specifies a width for each column in the group. The value
must be a number in pixels, a percentage of the table width, or a relative
length expressed as i* where i is an integer. A column with WIDTH="3*" will
be allotted three times the width of a column with WIDTH="1*". The value 0*
is equivalent to the minimum width necessary for the column's contents.
The ALIGN attribute specifies the horizontal alignment for each cell in the
column group. Possible values are left, center, right, justify, and char.
ALIGN=char aligns a cell's contents on the character given in the CHAR
attribute. The default value for the CHAR attribute is the decimal point of
the current language--a period in English. The CHAROFF attribute specifies
the offset to the first occurrence of the alignment character. The attribute's
value is a number in pixels or a percentage of the cell's width; CHAROFF="50%"
centers the alignment character horizontally in a cell.
The VALIGN attribute specifies the vertical position of a cell's contents.
Possible values are:
o top, which positions data at the top of the cell;
o middle, the default value, which centers the cell data vertically;
o bottom, which positions data at the bottom of the cell;
o baseline, which specifies that the first line of each cell in the row with
ALIGN=baseline should occur on a common baseline.
ΓòÉΓòÉΓòÉ 1.5.22. DD - Definition description ΓòÉΓòÉΓòÉ
DD - Definition Description
Syntax
<DD>...</DD>
Attribute Specifications
o common attributes
Contents
Inline elements, block-level elements
Contained in
DL
The DD element provides the definition of a term in a definition list. The
closing tag for DD is optional, but its use prevents common browser bugs with
style sheets.
DD may contain block-level elements such as P, H2, TABLE, and DL. This
allows definition lists to be nested, as in the following example:
<DL>
<DT><A NAME="spanning-tree">Spanning tree</A></DT>
<DD>
<P>
A spanning tree of a graph is a <A HREF="#tree">tree</A>
that contains all the vertices of the graph. There are two
main types of spanning trees:
</P>
<DL>
<DT>BFS spanning tree</DT>
<DD>
A spanning tree formed by a breadth-first search on the graph.
</DD>
<DT>DFS spanning tree</DT>
<DD>
A spanning tree formed by a depth-first search on the graph.
</DD>
</DL>
</DD>
<DT><A NAME=tree>Tree</A></DT>
<DD>
<P>
A tree is connected, undirected graph without cycles.
</P>
</DD>
</DL>
A DD element should generally be preceded by a DT element that gives the
term defined by the DD. A single definition term may have multiple definitions
associated with it, and a single definition may have multiple terms.
ΓòÉΓòÉΓòÉ 1.5.23. DEL - Deleted text ΓòÉΓòÉΓòÉ
DEL - Deleted Text
Syntax
<DEL>...</DEL>
Attribute Specifications
o CITE= URI (reason for deletion)
o DATETIME= Datetime (date and time of deletion)
o common attributes
Contents
Inline elements, block-level elements
Contained in
Inline elements, block-level elements
The DEL element contains content that has been deleted. This element is
useful in marking changes from one version of a document to the next. Through
style sheets, authors can suggest an appropriate rendering, such as not
displaying the deleted content or rendering the text with a strike-through
style.
DEL may be used as either a block-level element or an inline element. If
used as an inline element (e.g., within a P), then DEL may not contain any
block-level elements.
The optional CITE attribute of DEL gives a URI with information on why the
content was deleted. A brief explanation for the deletion can be given with
the TITLE attribute, which may be rendered as a "tooltip" by some browsers.
The optional DATETIME attribute specifies the date and time of the deletion.
The value is case-sensitive and of the form YYYY-MM-DDThh:mm:ssTZD. See the
values section for a full explanation of this format.
An example follows:
<DEL CITE="http://www.w3.org/TR/REC-html40/appendix/changes.html#h-A.1.3"
DATETIME="1997-12-19T00:00:00-05:00" TITLE="XMP is obsolete">
<P>The XMP element contains preformatted text in which markup
other than an end tag is treated as literal
text.</P>
</DEL>
Since DEL is poorly supported among browsers, authors may wish to use a font
style element such as STRIKE ( deprecated in HTML 4.0) to attempt to convey
the meaning of DEL to non-supporting visual browsers. The previous example
could also be marked up as follows:
<DEL CITE="http://www.w3.org/TR/REC-html40/appendix/changes.html#h-A.1.3"
DATETIME="1997-12-19T00:00:00-05:00" TITLE="XMP is obsolete">
<P><STRIKE>The XMP element is used for preformatted text in
which markup other than an end tag is treated as literal
text.</STRIKE></P>
</DEL>
ΓòÉΓòÉΓòÉ 1.5.24. DFN - Defined term ΓòÉΓòÉΓòÉ
DFN - Defined Term
Syntax
<DFN>...</DFN>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The DFN element denotes the defining instance of a term. Visual browsers
typically render DFN as italic text, but authors can suggest a rendering using
style sheets. Since DFN is a structural element, it carries meaning, making
it preferable to font style elements such as I when marking up the defining
instance of a term.
Netscape Navigator does not support the DFN element. In most cases, the lack
of support is not a significant problem; concerned authors could nest the DFN
element within an I element or another font style element.
ΓòÉΓòÉΓòÉ 1.5.25. DIR - Directory List ΓòÉΓòÉΓòÉ
DIR
Syntax
<DIR>...</DIR>
Attribute Specifications
o COMPACT (compact display)
o common attributes
Contents
One or more LI elements that cannot contain block-level elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The DIR element defines a directory list. The element contains one or more
LI elements that define the actual items of the list. The LI elements must
not contain block-level elements, which prevents DIRs from being nested.
The COMPACT attribute suggests that visual browsers render the list compactly,
perhaps with reduced spacing between items. This attribute is not well
supported among browsers.
DIR is deprecated in HTML 4.0 in favor of UL.
ΓòÉΓòÉΓòÉ 1.5.26. DIV - Generic block-level container ΓòÉΓòÉΓòÉ
DIV - Generic Block-level Container
Syntax
<DIV>...</DIV>
Attribute Specifications
o ALIGN=[ left | center | right | justify ] (horizontal alignment)
o common attributes
Contents
Inline elements, block-level elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The DIV element defines a generic block-level container, allowing authors to
provide style or language information to blocks of content. The element may
contain any inline or block-level element, including another DIV.
The DIV element is most useful in combination with the CLASS, ID, or LANG
attributes. For example, a navigation bar could be contained within a DIV
marked as CLASS=navbar, allowing the author to use style sheets to easily
change the background of all navigation bars on a site, or to eliminate
navigation bars when printing.
The deprecated ALIGN attribute suggests the horizontal alignment for the
content of the division on visual browsers. Possible values are left, right,
center, and justify. <CENTER> is a slightly better-supported alias for <DIV
ALIGN=center>, though both methods of centering are deprecated in favor of
style sheets, which provide greater flexibility in suggesting alignment.
SPAN is a text-level equivalent of DIV for use within paragraphs and inline
elements.
ΓòÉΓòÉΓòÉ 1.5.27. DL - Definition list ΓòÉΓòÉΓòÉ
DL - Definition List
Syntax
<DL>...</DL>
Attribute Specifications
o COMPACT (compact display)
o common attributes
Contents
One or more DT or DD elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The DL element defines a definition list. An entry in the list is created
using the DT element for the term being defined and the DD element for the
definition of the term.
A definition list can have multiple terms for a given definition as well as
multiple definitions for a given term. Authors can also give a term without a
corresponding definition, and vice versa, but such a structure rarely makes
sense.
An example follows:
<DL>
<DT>Block-level elements</DT>
<DD>
<P>
In HTML, block-level elements may generally contain
inline elements and other block-level elements. They are
usually formatted differently than inline elements,
typically on a new line in visual browsers.
</P>
</DD>
<DT>Inline elements</DT> <DT>Text-level elements</DT>
<DD>
<P>
Inline (or text-level) elements generally only contain
character data and other inline elements.
</P>
</DD>
</DL>
The DL element can be adapted for use with structures that are not strict
terms and definitions, a practice that is justified when other HTML elements
cannot adequately describe a structure. Some examples follow:
<H1>Community Calendar</H1>
<DL CLASS=calendar>
<DT>March 8</DT>
<DD>
The Symphony Orchestra presents <CITE>A Rising Star</CITE>
at the Anderson Center. Call 555-1234 for details.
</DD>
<DT>March 10</DT>
<DD>
Bereaved Families Support Night, 7:00 to 9:00 at
523 Main <ABBR TITLE=Street>St.</ABBR>
</DD>
</DL>
<DL CLASS=play>
<DT>Brutus</DT>
<DD CLASS="role Brutus">
<P>
I kiss thy hand, but not in flattery, Caesar;<BR>
Desiring thee that Publius Cimber may<BR>
Have an immediate freedom of repeal.
</P>
</DD>
<DT>Caesar</DT>
<DD CLASS="role Caesar">
<P>
What, Brutus!
</P>
</DD>
<DT>Cassius</DT>
<DD CLASS="role Cassius">
<P>
Pardon, Caesar; Caesar, pardon:<BR>
As low as to thy foot doth Cassius fall,<BR>
To beg enfranchisement for Publius Cimber.
</P>
</DD>
</DL>
Note the use of the CLASS attribute in the preceding examples. This allows
the author to easily suggest, through style sheets, a distinguishing
presentation for different kinds of definition lists.
In addition to the common attributes shared by most elements, DL takes a
COMPACT attribute. This attribute, deprecated in HTML 4.0 and poorly
supported among browsers, suggests that visual browsers render the list
compactly, perhaps with reduced spacing between items.
ΓòÉΓòÉΓòÉ 1.5.28. DT - Definition term ΓòÉΓòÉΓòÉ
DT - Definition Term
Syntax
<DT>...</DT>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
DL
The DT element defines a term in a definition list. The closing tag for DT
is optional, but its use prevents common browser bugs with style sheets. Note
that DT cannot contain block-level elements such as P and H2.
A DT element should generally be followed by a DD element that provides the
definition for the term given by the DT. A single definition term may have
multiple definitions associated with it, and a single definition may have
multiple terms.
ΓòÉΓòÉΓòÉ 1.5.29. EM - Emphasis ΓòÉΓòÉΓòÉ
EM - Emphasis
Syntax
<EM>...</EM>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The EM element gives emphasis to its contents. Visual browsers typically
render EM as italic text, but authors can suggest a rendering using style
sheets. Since EM is a structural element, it carries meaning, making it
preferable to font style elements such as I when emphasis is the intended
meaning.
For strong emphasis, use the STRONG element.
ΓòÉΓòÉΓòÉ 1.5.30. FIELDSET - Form control group ΓòÉΓòÉΓòÉ
FIELDSET - Form Control Group
Syntax
<FIELDSET>...</FIELDSET>
Attribute Specifications
o common attributes
Contents
A LEGEND element followed by zero or more block-level elements and
inline elements
Contained in
APPLET, BLOCKQUOTE, BODY, CENTER, DD, DEL, DIV, FIELDSET, FORM,
IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The FIELDSET element defines a form control group. By grouping related form
controls, authors can divide a form into smaller, more manageable parts,
improving the usability disaster that can strike when confronting users with
too many form controls. The grouping provided by FIELDSET also helps the
accessibility of forms to those using aural browsers by allowing these users to
more easily orient themselves when filling in a large form.
While FIELDSET is not widely supported by current browsers, it can be used
safely by explicitly closing any preceding P element with </P> or by
including an empty P prior to the FIELDSET. This causes non-supporting
browsers to infer the start of a block-level element even though they ignore
the block-level FIELDSET element.
The content of a FIELDSET element must begin with a LEGEND to provide a
caption for the group of controls. Following the LEGEND, FIELDSET may contain
any inline or block-level element, including another FIELDSET.
An example follows:
<FORM METHOD=post ACTION="/cgi-bin/order.cgi">
<FIELDSET>
<LEGEND ACCESSKEY=I>Contact Information</LEGEND>
<TABLE>
<TR>
<TD>
<LABEL FOR=name ACCESSKEY=N>Name:</LABEL>
</TD>
<TD>
<INPUT TYPE=text NAME=name ID=name>
</TD>
</TR>
<TR>
<TD>
<LABEL FOR=email ACCESSKEY=E>E-mail Address:</LABEL>
</TD>
<TD>
<INPUT TYPE=text NAME=email ID=email>
</TD>
</TR>
<TR>
<TD>
<LABEL FOR=addr ACCESSKEY=A>Mailing Address:</LABEL>
</TD>
<TD>
<TEXTAREA NAME=address ID=addr ROWS=4 COLS=40></TEXTAREA>
</TD>
</TR>
</TABLE>
</FIELDSET>
<FIELDSET>
<LEGEND ACCESSKEY=O>Ordering Information</LEGEND>
<P>Please select the product(s) that you wish to order:</P>
<P>
<LABEL ACCESSKEY=3>
<INPUT TYPE=checkbox NAME=products VALUE="HTML 3.2 Reference">
<A HREF="/reference/wilbur/">HTML 3.2 Reference</A>
</LABEL>
<BR>
<LABEL ACCESSKEY=4>
<INPUT TYPE=checkbox NAME=products VALUE="HTML 4.0 Reference">
<A HREF="/reference/html40/">HTML 4.0 Reference</A>
</LABEL>
<BR>
<LABEL ACCESSKEY=S>
<INPUT TYPE=checkbox NAME=products VALUE="CSS Guide">
<A HREF="/reference/css/">Cascading Style Sheets Guide</A>
</LABEL>
</P>
</FIELDSET>
<FIELDSET>
<LEGEND ACCESSKEY=C>Credit Card Information</LEGEND>
<P>
<LABEL ACCESSKEY=V>
<INPUT TYPE=radio NAME=card VALUE=visa> Visa
</LABEL>
<LABEL ACCESSKEY=M>
<INPUT TYPE=radio NAME=card VALUE=mc> MasterCard
</LABEL>
<BR>
<LABEL ACCESSKEY=u>
Number: <INPUT TYPE=text NAME=number>
</LABEL>
<BR>
<LABEL ACCESSKEY=E>
Expiry: <INPUT TYPE=text NAME=expiry>
</LABEL>
</P>
</FIELDSET>
<P>
<INPUT TYPE=submit VALUE="Submit order">
<INPUT TYPE=reset VALUE="Clear order form"> </P>
</FORM>
ΓòÉΓòÉΓòÉ 1.5.31. FONT - Font change ΓòÉΓòÉΓòÉ
FONT - Font Change
Syntax
<FONT>...</FONT>
Attribute Specifications
o SIZE= CDATA (font size adjustment)
o COLOR= Color (font color adjustment)
o FACE= CDATA (font face adjustment)
o core attributes
o internationalization attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements except PRE
The FONT element, deprecated in HTML 4.0 in favor of style sheets, allows
authors to suggest rudimentary font changes. Use of the FONT element brings
numerous usability and accessibility problems, as discussed in the article
What's Wrong With FONT?
The least harmful use of the FONT element is in suggesting relative changes in
font size with <FONT SIZE="+1"> or <FONT SIZE="-1">. These tags increment or
decrement the font size relative to the size specified in the BASEFONT
element, or relative to a base size of 3 if no BASEFONT element is used.
Sizes are based on a seven-point scale (1..7) that is browser dependent.
While authors can specify SIZE values such as -2 and +3, as well as absolute
values such as 1, these kinds of changes are strongly discouraged due to the
sensitivity some users have to different font sizes. While a value like -2
may look right to you with your eyesight and user settings, it could easily be
unreadable to a user with different eyesight and user settings.
The COLOR attribute suggests a text color. While most browsers allow users to
override author color changes, the widely used Netscape Navigator 2.x, 3.x, and
4.x do not override colors specified with FONT. This makes the COLOR
attribute very dangerous from an accessibility point of view.
Authors often use the COLOR attribute as a form of emphasis or to indicate a
heading. In these cases, use of structural HTML (e.g., STRONG, H1) along
with a style sheet provides a more flexible, accessible document.
The FACE attribute gives a comma-separated list of font faces in which to
display text. The fonts are listed in order of preference, so that if the
browser does not have the first font listed, it will try the second, then the
third, and so on.
The FONT element is an inline element, meaning that it cannot contain
block-level elements such as P and TABLE. Again, style sheets provide
much more flexibility in suggesting font styles.
ΓòÉΓòÉΓòÉ 1.5.32. FORM - Interactive form ΓòÉΓòÉΓòÉ
FORM - Interactive Form
Syntax
<FORM>...</FORM>
Attribute Specifications
o ACTION= URI (form handler)
o METHOD=[ get | post ] (HTTP method for submitting form)
o ENCTYPE= ContentType (content type to submit form as)
o ACCEPT-CHARSET= Charsets (supported character encodings)
o TARGET= FrameTarget (frame to render form result in)
o ONSUBMIT= Script (form was submitted)
o ONRESET= Script (form was reset)
o common attributes
Contents
o In HTML 4.0 Strict, one or more SCRIPT or block-level elements except
FORM
o In HTML 4.0 Transitional, inline elements or block-level elements except
FORM
Contained in
APPLET, BLOCKQUOTE, BODY, CENTER, DD, DEL, DIV, FIELDSET, IFRAME,
INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The FORM element defines an interactive form. The element should contain form
controls-- INPUT, SELECT, TEXTAREA, and BUTTON--through which the user
interacts.
When the user submits the form, through an INPUT or BUTTON element with
TYPE=submit, the form values are submitted to the URI given in FORM's required
ACTION attribute. ACTION usually points to a CGI script or Java servlet
that handles the form submission.
A mailto URI (e.g., mailto:liam@htmlhelp.com) is also allowed as an ACTION,
but this is not supported by all browsers. Non-supporting browsers such as
Microsoft Internet Explorer 3.x typically will open a blank e-mail message when
the user submits a mailto form. Even on supporting browsers, mailto forms are
troublesome in that they fail to provide feedback to the user after the form
submission.
Free CGI scripts exist for handling forms; some are even remotely hosted for
authors whose providers refuse to allow CGI scripts to be run locally.
How the form input is sent to the server depends on the METHOD and ENCTYPE
attributes. When the METHOD is get (the default), the form input is
submitted as an HTTP GET request with ?form_data appended to the URI
specified in the ACTION attribute.
Using the get method allows the form submission to be contained completely in
a URL. This can be advantageous in that it permits bookmarking in current
browsers, but it also prevents form data from containing non-ASCII characters
such as "щ" and "й". As well, the amount of form data that can be handled by
the get method is limited by the maximum length of the URL that the server
and browser can process. To be safe, any form whose input might contain
non-ASCII characters or more than 100 characters should use METHOD=post.
With a METHOD value of post, the form input is submitted as an HTTP POST
request with the form data sent in the body of the request. Most current
browsers are unable to bookmark POST requests, but POST does not entail the
character encoding and length restrictions imposed by GET.
The ENCTYPE attribute specifies the content type used in submitting the form,
and defaults to application/x-www-form-urlencoded. This content type results
in name/value pairs sent to the server as name1=value1&name2=value2... with
space characters replaced by "+" and reserved characters (like "#") replaced by
"%HH" where HH is the ASCII code of the character in hexadecimal. Line
breaks are encoded as "%0D%0A"--a carriage return followed by a line feed.
Authors should generally only use a different ENCTYPE when the form includes a
TYPE=file INPUT element, in which case the ENCTYPE should be
multipart/form-data and the METHOD must be post. The format of
multipart/form-data requests is given in RFC 1867.
Tools such as cg-eye allow authors to easily create and view a request,
simulating the submission of a form. However, authors often do not need to
concern themselves with the exact format of the submission; CGI libraries
including CGI.pm transparently handle get and post submissions sent as
application/x-www-form-urlencoded or multipart/form-data.
The ACCEPT-CHARSET attribute specifies a list of character encodings that are
accepted by the form handler. The value consists of a list of "charsets"
separated by commas and/or spaces. The default value is UNKNOWN and is
usually considered to be the character encoding used to transmit the document
containing the FORM.
The TARGET attribute is used with frames to specify in which frame the form
response should be rendered. If no frame with such a name exists, the response
is rendered in a new window unless overridden by the user. Special frame names
begin with an underscore:
o _blank renders the response in a new, unnamed window
o _self renders the response in the current frame (useful for overriding a
BASE TARGET)
o _parent renders the response in the immediate FRAMESET parent
o _top renders the response in the full, unframed window
The FORM element also takes a number of attributes to specify client-side
scripting actions for various events. In addition to the core events common
to most elements, INPUT accepts the following event attributes:
o ONSUBMIT, when the form is submitted;
o ONRESET, when the form is reset.
ΓòÉΓòÉΓòÉ 1.5.33. FRAME - Frame ΓòÉΓòÉΓòÉ
FRAME - Frame
Syntax
<FRAME>
Attribute Specifications
o NAME= CDATA (name of frame)
o SRC= URI (content of frame)
o LONGDESC= URI (long description of frame)
o FRAMEBORDER=[ 1 | 0 ] (frame border)
o MARGINWIDTH= Pixels (margin width)
o MARGINHEIGHT= Pixels (margin height)
o NORESIZE (disallow frame resizing)
o SCROLLING=[ yes | no | auto ] (ability to scroll)
o core attributes
Contents
Empty
Contained in
FRAMESET
The FRAME element defines a frame--a rectangular subspace within a Frameset
document. Each FRAME must be contained within a FRAMESET that defines the
dimensions of the frame.
The SRC attribute provides the URI of the frame's content, which is typically
an HTML document. If the frame's content is an image, video, or similar
object, and if the object cannot be described adequately using the TITLE
attribute of FRAME, then authors should use the LONGDESC attribute to provide
the URI of a full HTML description of the object.
For better accessibility to disabled users and better indexing with search
engines, authors should not use an image or similar object as the content of a
frame. Rather, the object should be embedded within an HTML document to allow
the indexing of keywords and easier provision of alternate content.
The NAME attribute gives a name to the frame for use with the TARGET
attribute of the A, AREA, BASE, FORM, and LINK elements. The NAME
attribute value must begin with a character in the range A-Z or a-z.
The NAME should be human-readable and based on the content of the frame since
non-windows browsers may use the NAME as a title for presenting a list of
frames to the user. For example, NAME=left would be inappropriate since it
says nothing about the content while NAME=nav would be inappropriate since it
is not very human-readable. More suitable would be NAME=Content and
NAME=Navigation. The TITLE attribute can also be used to provide a slightly
longer title for the frame, though this is not widely supported by current
browsers.
An example follows:
<FRAMESET ROWS="*,100">
<FRAMESET COLS="40%,*">
<FRAME NAME="Menu" SRC="nav.html" TITLE="Menu">
<FRAME NAME="Content" SRC="main.html" TITLE="Content">
</FRAMESET>
<FRAME NAME="Ad" SRC="ad.html" TITLE="Advertisement">
<NOFRAMES>
<BODY>
<H1>Table of Contents</H1>
<UL>
<LI>
<A HREF="reference/html40/">HTML 4.0 Reference</A>
</LI>
<LI>
<A HREF="reference/wilbur/">HTML 3.2 Reference</A>
</LI>
<LI>
<A HREF="reference/css/">CSS Guide</A>
</LI>
</UL>
<P>
<IMG SRC="ad.gif" ALT="Ad: Does your bank charge too much?">
</P>
</BODY>
</NOFRAMES>
</FRAMESET>
The FRAME element also accepts a number of attributes to specify the
presentation on visual browsers. Style sheets provide a more flexible method
of defining the presentation of frames, but the element's presentational
attributes are more widely supported.
The FRAMEBORDER attribute specifies whether or not the frame has a visible
border. The default value, 1, tells the browser to draw a border between the
frame and all adjoining frames. The value 0 indicates that no border should
be drawn, though borders from other frames will override this.
To fully remove the border, some browsers also require the use of other,
non-standard attributes. See How do I remove the border around frames? for
more details.
Note that removing the border of a frame takes away the user's ability to
resize the frame on most browsers.
The MARGINWIDTH and MARGINHEIGHT attributes define the number of pixels to
use as the left/right margins and top/bottom margins, respectively, within the
frame. The value must be greater than one pixel.
The boolean NORESIZE attribute prevents the user from resizing the frame.
This attribute should never be used in a user-friendly Web site.
The SCROLLING attribute specifies whether scrollbars are provided for the
frame. The default value, auto, generates scrollbars only when necessary. The
value yes gives scrollbars at all times, and the value no suppresses
scrollbars--even when they are needed to see all the content. The value no
should never be used.
ΓòÉΓòÉΓòÉ 1.5.34. FRAMESET - Frameset ΓòÉΓòÉΓòÉ
FRAMESET - Frameset
Syntax
<FRAMESET>...</FRAMESET>
Attribute Specifications
o ROWS= MultiLengths (row lengths)
o COLS= MultiLengths (column lengths)
o ONLOAD= Script (all frames have been loaded)
o ONUNLOAD= Script (all frames have been removed)
o core attributes
Contents
One or more FRAMESET and FRAME elements, as well as an optional
NOFRAMES
Contained in
HTML
The FRAMESET element is a frame container for dividing a window into
rectangular subspaces called frames. In a Frameset document, the outermost
FRAMESET element takes the place of BODY and immediately follows the HEAD.
The FRAMESET element contains one or more FRAMESET or FRAME elements, along
with an optional NOFRAMES element to provide alternate content for browsers
that do not support frames or have frames disabled. A meaningful NOFRAMES
element should always be provided and should at the very least contain links to
the main frame or frames.
The ROWS and COLS attributes define the dimensions of each frame in the set.
Each attribute takes a comma-separated list of lengths, specified in pixels, as
a percentage, or as a relative length. A relative length is expressed as i*
where i is an integer. For example, a frameset defined with ROWS="3*,*" (*
is equivalent to 1*) will have its first row allotted three times the height of
the second row.
The values specified for the ROWS attribute give the height of each row, from
top to bottom. The COLS attribute gives the width of each column from left to
right. If ROWS or COLS is omitted, the implied value for the attribute is
100%. If both attributes are specified, a grid is defined and filled
left-to-right then top-to-bottom.
The following example sets up a grid with two rows and three columns:
<FRAMESET ROWS="70%,30%" COLS="33%,33%,34%">
<FRAME NAME="Photo1" SRC="Row1_Column1.html">
<FRAME NAME="Photo2" SRC="Row1_Column2.html">
<FRAME NAME="Photo3" SRC="Row1_Column3.html">
<FRAME NAME="Caption1" SRC="Row2_Column1.html">
<FRAME NAME="Caption2" SRC="Row2_Column2.html">
<FRAME NAME="Caption3" SRC="Row2_Column3.html">
<NOFRAMES>
<BODY>
<H1>Table of Contents</H1>
<UL>
<LI>
<A HREF="Row1_Column1.html">Photo 1</A>
(<A HREF="Row2_Column1.html">Caption</A>)
</LI>
<LI>
<A HREF="Row1_Column2.html">Photo 2</A>
(<A HREF="Row2_Column2.html">Caption</A>)
</LI>
<LI>
<A HREF="Row1_Column3.html">Photo 3</A>
(<A HREF="Row2_Column3.html">Caption</A>)
</LI>
</UL>
</BODY>
</NOFRAMES>
</FRAMESET>
The next example features nested FRAMESET elements to define two frames in the
first row and one frame in the second row:
<FRAMESET ROWS="*,100">
<FRAMESET COLS="40%,*">
<FRAME NAME="Menu" SRC="nav.html" TITLE="Menu">
<FRAME NAME="Content" SRC="main.html" TITLE="Content">
</FRAMESET>
<FRAME NAME="Ad" SRC="ad.html" TITLE="Advertisement">
<NOFRAMES>
<BODY>
<H1>Table of Contents</H1>
<UL>
<LI>
<A HREF="reference/html40/">HTML 4.0 Reference</A>
</LI>
<LI>
<A HREF="reference/wilbur/">HTML 3.2 Reference</A>
</LI>
<LI>
<A HREF="reference/css/">CSS Guide</A>
</LI>
</UL>
<P>
<IMG SRC="ad.gif" ALT="Ad: Does your bank charge too much?">
</P>
</BODY>
</NOFRAMES>
</FRAMESET>
When pixel lengths are used, they should always be combined with a relative
length to handle various window sizes. Pixel lengths should only be used when
the frame consists primarily of images or other objects with a fixed size in
pixels. Due to their ability to adapt to different window sizes, percentages
and relative lengths are generally preferred.
The FRAMESET element also accepts ONLOAD and ONUNLOAD attributes to specify
client-side scripting actions to perform when the frames have all been loaded
or removed.
ΓòÉΓòÉΓòÉ 1.5.35. H1 - Level-one heading ΓòÉΓòÉΓòÉ
H1 - Level-one Heading
Syntax
<H1>...</H1>
Attribute Specifications
o ALIGN=[ left | center | right | justify ] (horizontal alignment)
o common attributes
Contents
Inline elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DEL, DD, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The H1 element defines a level-one heading. A document generally should have
exactly one H1 element to mark the most important heading.
The deprecated ALIGN attribute suggests the horizontal alignment for the
heading on visual browsers. Possible values are left, right, center, and
justify. Style sheets provide greater flexibility in suggesting alignment.
Visual browsers typically render H1 in a large, bold font. Authors can suggest
a presentation for H1 through style sheets. The following CSS ruleset
suggests a presentation for all H1 elements:
h1 { color: #c33;
background: transparent;
font-weight: bold;
text-align: center
}
Authors should not choose a heading level based on the font size commonly used
by visual browsers. The heading level should be chosen based on the heading's
importance and placement in the document. An H1 is typically used as the main
heading for a document.
ΓòÉΓòÉΓòÉ 1.5.36. H2 - Level-two heading ΓòÉΓòÉΓòÉ
H2 - Level-two Heading
Syntax
<H2>...</H2>
Attribute Specifications
o ALIGN=[ left | center | right | justify ] (horizontal alignment)
o common attributes
Contents
Inline elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DEL, DD, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The H2 element defines a level-two heading. This heading is more important
than an H3 but less important than an H1.
The deprecated ALIGN attribute suggests the horizontal alignment for the
heading on visual browsers. Possible values are left, right, center, and
justify. Style sheets provide greater flexibility in suggesting alignment.
Visual browsers typically render H2 in a large, bold font. Authors can suggest
a presentation for H2 through style sheets. The following CSS ruleset
suggests a presentation for all H2 elements:
h2 {
color: #00008b;
background: transparent;
font-weight: bold;
margin-left: 2%;
margin-right: 2%
}
Authors should not choose a heading level based on the font size commonly used
by visual browsers. The heading level should be chosen based on the heading's
importance and placement in the document. An H2 is typically used within a
section headed by an H1.
ΓòÉΓòÉΓòÉ 1.5.37. H3 - Level-three heading ΓòÉΓòÉΓòÉ
H3 - Level-three Heading
Syntax
<H3>...</H3>
Attribute Specifications
o ALIGN=[ left | center | right | justify ] (horizontal alignment)
o common attributes
Contents
Inline elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DEL, DD, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The H3 element defines a level-three heading. This heading is more important
than an H4 but less important than an H2.
The deprecated ALIGN attribute suggests the horizontal alignment for the
heading on visual browsers. Possible values are left, right, center, and
justify. Style sheets provide greater flexibility in suggesting alignment.
Visual browsers typically render H3 in a bold font. Authors can suggest a
presentation for H3 through style sheets. The following CSS ruleset
suggests a presentation for all H3 elements:
h3 {
color: #006400;
background: transparent;
margin-left: 4%;
margin-right: 4%;
font-weight: bold
}
Authors should not choose a heading level based on the font size commonly used
by visual browsers. The heading level should be chosen based on the heading's
importance and placement in the document. An H3 is typically used within a
section headed by an H2.
ΓòÉΓòÉΓòÉ 1.5.38. H4 - Level-four heading ΓòÉΓòÉΓòÉ
H4 - Level-four Heading
Syntax
<H4>...</H4>
Attribute Specifications
o ALIGN=[ left | center | right | justify ] (horizontal alignment)
o common attributes
Contents
Inline elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DEL, DD, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The H4 element defines a level-four heading. This heading is more important
than an H5 but less important than an H3.
The deprecated ALIGN attribute suggests the horizontal alignment for the
heading on visual browsers. Possible values are left, right, center, and
justify. Style sheets provide greater flexibility in suggesting alignment.
Visual browsers typically render H4 in a bold font. Authors can suggest a
presentation for H4 through style sheets. The following CSS ruleset
suggests a presentation for all H4 elements:
h4 {
margin-left: 6%;
margin-right: 6%;
font-weight: bold
}
Authors should not choose a heading level based on the font size commonly used
by visual browsers. The heading level should be chosen based on the heading's
importance and placement in the document. An H4 is typically used within a
section headed by an H3.
ΓòÉΓòÉΓòÉ 1.5.39. H5 - Level-five heading ΓòÉΓòÉΓòÉ
H5 - Level-five Heading
Syntax
<H5>...</H5>
Attribute Specifications
o ALIGN=[ left | center | right | justify ] (horizontal alignment)
o common attributes
Contents
Inline elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DEL, DD, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The H5 element defines a level-five heading. This heading is more important
than an H6 but less important than an H4.
The deprecated ALIGN attribute suggests the horizontal alignment for the
heading on visual browsers. Possible values are left, right, center, and
justify. Style sheets provide greater flexibility in suggesting alignment.
Visual browsers typically render H5 in a small, bold font. Authors can suggest
a presentation for H5 through style sheets. The following CSS ruleset
suggests a presentation for all H5 elements:
h5 {
margin-left: 6%;
margin-right: 6%;
font-size: 110%;
font-weight: bold
}
Authors should not choose a heading level based on the font size commonly used
by visual browsers. The heading level should be chosen based on the heading's
importance and placement in the document. An H5 is typically used within a
section headed by an H4.
ΓòÉΓòÉΓòÉ 1.5.40. H6 - Level-six heading ΓòÉΓòÉΓòÉ
H6 - Level-six Heading
Syntax
<H6>...</H6>
Attribute Specifications
o ALIGN=[ left | center | right | justify ] (horizontal alignment)
o common attributes
Contents
Inline elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DEL, DD, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The H6 element defines a level-six heading. This heading is less important
than an H5.
The deprecated ALIGN attribute suggests the horizontal alignment for the
heading on visual browsers. Possible values are left, right, center, and
justify. Style sheets provide greater flexibility in suggesting alignment.
Visual browsers typically render H6 in a small, bold font. Authors can suggest
a presentation for H6 through style sheets. The following CSS ruleset
suggests a presentation for all H6 elements:
h6 {
margin-left: 6%;
margin-right: 6%;
font-size: 105%;
font-weight: bold
}
Authors should not choose a heading level based on the font size commonly used
by visual browsers. The heading level should be chosen based on the heading's
importance and placement in the document. An H6 is typically used within a
section headed by an H5.
ΓòÉΓòÉΓòÉ 1.5.41. HEAD - Document head ΓòÉΓòÉΓòÉ
HEAD - Document Head
Syntax
<HEAD>...</HEAD>
Attribute Specifications
o PROFILE= URI (dictionary of meta info)
o internationalization attributes
Contents
Exactly one TITLE element, optional BASE and ISINDEX elements, and
zero or more SCRIPT, STYLE, META, LINK, or OBJECT elements
Contained in
HTML
The HEAD element contains header information about the document, such as its
title, keywords, description, and style sheet. HEAD is required in all
documents, but its start and end tags are always optional. The HEAD element
is followed by the BODY in HTML 4.0 Strict and Transitional documents; in
HTML 4.0 Frameset documents, the HEAD is followed by a FRAMESET element.
Content in the HEAD is generally not rendered, with the exception of the
required TITLE element. If the </HEAD> end tag is omitted, the first BODY
or FRAMESET element infers the end of the HEAD.
The optional PROFILE attribute of HEAD gives the location of a metadata
profile. A profile defines properties that may be used by META and LINK
elements within the HEAD. There is no prescribed format for profiles.
Work is currently underway on improving the use of metadata on the Web. See the
W3C's Metadata and Resource Description area for the latest information.
ΓòÉΓòÉΓòÉ 1.5.42. HR - Horizontal rule ΓòÉΓòÉΓòÉ
HR - Horizontal Rule
Syntax
<HR>
Attribute Specifications
o ALIGN=[ left | center | right ] (horizontal alignment)
o NOSHADE (solid line)
o SIZE= Pixels (line height)
o WIDTH= Length (line width)
o core attributes
o common events
Contents
Empty
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The HR element defines a horizontal rule for visual browsers. While this
element is inherently presentational, it can be used structurally as a section
divider. However, for greater flexibility the HR element can be replaced with
the border-bottom or border-top properties of Cascading Style Sheets. For
example, the following style rule would suggest a horizontal line above all
DIV elements with CLASS=navbar:
div.navbar { border-top: solid medium navy }
HR's deprecated ALIGN attribute suggests the horizontal alignment of the
line. Possible values are left, right, and center. The deprecated WIDTH
attribute specifies the width of the line as a percentage or a number of
pixels. If a width is specified, percentages are generally preferred since
they adjust to varying window sizes. The width property of Cascading Style
Sheets provides greater flexibility in suggesting the width of horizontal
rules.
The boolean NOSHADE attribute suggests that the rule be rendered as a solid
line rather than the groove style commonly used. The SIZE attribute suggests
the height of the line in pixels. These attributes are both deprecated in
favor of style sheets.
ΓòÉΓòÉΓòÉ 1.5.43. HTML - HTML document ΓòÉΓòÉΓòÉ
HTML - HTML Document
Syntax
<HTML>...</HTML>
Attribute Specifications
o VERSION= CDATA (HTML version)
o internationalization attributes
Contents
o In HTML 4.0 Strict and Transitional: HEAD followed by BODY
o In HTML 4.0 Frameset: HEAD followed by FRAMESET
Contained in
Not applicable--HTML is a top-level element
The HTML element contains the HTML document, made up of the HEAD followed by
the BODY, except in Frameset documents where the FRAMESET element replaces
the BODY. The start and end tags of the HTML element are both optional.
The LANG attribute is typically set on the HTML element to specify the base
language of the document. The language should be specified according to RFC
1766; examples include en for English, en-US for American English, and ja
for Japanese.
The deprecated VERSION attribute specifies the Document Type Definition (DTD)
that describes the document. This attribute should not be used since the
DOCTYPE declaration makes it redundant.
ΓòÉΓòÉΓòÉ 1.5.43.1. DOCTYPE - Document Type Declaration ΓòÉΓòÉΓòÉ
DOCTYPE - Document Type Declaration
Each HTML document must begin with a document type declaration that declares
which version of HTML the document adheres to. HTML 4.0 comes in three flavors,
each with a different DOCTYPE:
HTML 4.0 Strict
HTML 4.0 Strict is a trimmed down version of HTML 4.0 that
emphasizes structure over presentation. Deprecated elements and
attributes (including most presentational attributes), frames, and
link targets are not allowed in HTML 4.0 Strict . By writing to HTML
4.0 Strict authors can achieve accessible, structurally rich
documents that easily adapt to style sheets and different browsing
situations. However, since many browsers lack full support for style
sheets, HTML 4.0 Strict documents may look bland on common visual
browsers such as Netscape Navigator 3.x.
The document type declaration for HTML 4.0 Strict is
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN"
"http://www.w3.org/TR/REC-html40/strict.dtd">
HTML 4.0 Transitional
HTML 4.0 Transitional includes all elements and attributes of HTML
4.0 Strict but adds presentational attributes, deprecated elements,
and link targets. HTML 4.0 Transitional recognizes the relatively
poor browser support for style sheets, allowing many HTML
presentation features to be used as a transition towards HTML 4.0
Strict.
The document type declaration for HTML 4.0 Transitional is
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional //EN"
"http://www.w3.org/TR/REC-html40/loose.dtd">
HTML 4.0 Frameset
HTML 4.0 Frameset is a variant of HTML 4.0 Transitional for documents
that use frames. The FRAMESET element replaces the BODY in a Frameset
document.
The document type declaration for HTML 4.0 Frameset is
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Frameset//EN"
"http://www.w3.org/TR/REC-html40/frameset.dtd">
ΓòÉΓòÉΓòÉ 1.5.44. I - Italic text ΓòÉΓòÉΓòÉ
I - Italic Text
Syntax
<I>...</I>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The I element suggests that text be rendered as italic text. In most cases, use
of a phrase elemens such as EM, DFN, VAR, or CITE is more appropriate since
these elements express the meaning of the text more clearly.
The I element is a suitable choice for marking a structure for which no phrase
elemens exists. For example, foreign phrases and taxonomic names have no
structural element in HTML 4.0, but italic text is often an appropriate visual
rendering:
<H1><I LANG=fr>Chacun son go√t !</I></H1>
<P>Some people prefer dogs--
<I CLASS=species>Canis familiaris</I>
--while others are eternal lovers of cats--
<I CLASS=species>Felis cattus</I>.
Note the use of the CLASS and LANG attributes to add structural significance to
the I elements. This allows greater flexibility when applying style sheets to
different kinds of italic text.
ΓòÉΓòÉΓòÉ 1.5.45. IFRAME - Inline frame ΓòÉΓòÉΓòÉ
IFRAME - Inline Frame
Syntax
<IFRAME>...</IFRAME>
Attribute Specifications
o SRC= URI (URI of frame content)
o NAME= CDATA (name of frame)
o LONGDESC= URI (link to long description)
o WIDTH= Length (frame width)
o HEIGHT= Length (frame height)
o ALIGN=[ top | middle | bottom | left | right ] (frame alignment)
o FRAMEBORDER=[ 1 | 0 ] (frame border)
o MARGINWIDTH= Pixels (margin width)
o MARGINHEIGHT= Pixels (margin height)
o SCROLLING=[ yes | no | auto ] (ability to scroll)
o core attributes
Contents
Inline elements, block-level elements
Contained in
Inline elements, block-level elements
The IFRAME element defines an inline frame for the inclusion of external
objects including other HTML documents. IFRAME provides a subset of the
functionality of OBJECT; the only advantage to IFRAME is that an inline frame
can act as a target for other links. OBJECT is more widely supported than
IFRAME, and, unlike IFRAME, OBJECT is included in HTML 4.0 Strict.
IFRAME's SRC attribute provides the location of the frame content--typically
an HTML document. The optional NAME attribute specifies the name of the inline
frame, allowing links to target the frame.
The content of the IFRAME element is used as an alternative for browsers that
are not configured to show or do not support inline frames. The content may
consist of inline or block-level elements, though any block-level elements
must be allowed inside the containing element of IFRAME. For example, an IFRAME
within an H1 cannot contain an H2, but an IFRAME within a DIV can contain
any block-level elements.
The LONGDESC attribute gives the URI of a long description of the frame's
contents. This is particularly useful for full descriptions of embedded
objects. Note that LONGDESC describes the frame content while the content of
the IFRAME element acts as a replacement when the external resource cannot be
inlined.
An example follows:
<IFRAME SRC="recipe.html" TITLE="The Famous Recipe">
<!-- Alternate
content for non-supporting browsers -->
<H2>The Famous Recipe</H2>
<H3>Ingredients</H3>
...
</IFRAME>
The WIDTH and HEIGHT attributes specify the dimensions of the inline frame in
pixels or as a percentage of the available space. The FRAMEBORDER attribute
specifies whether or not a border should be drawn. The default value of 1
results in a border while a value of 0 suppresses the border. Style sheets
allow greater flexibility in suggesting the border presentation.
The ALIGN attribute specifies the alignment of the inline frame. The values
top, middle, and bottom specify the frame's position with respect to
surrounding content on its left and right.
ALIGN=middle aligns the center of the frame with the current baseline. To
center the frame horizontally on the page, place the frame in a centered block,
e.g.,
<P ALIGN=center>
<IFRAME SRC="foo.html" WIDTH=300 HEIGHT=100></IFRAME>
</P>
The other ALIGN values, left and right, specify a floating frame; the frame
is placed at the left or right margin and content flows around it. To place
content below the frame, use <BR CLEAR=left|right|all> as appropriate.
The vertical-align and float properties of Cascading Style Sheets provide
more flexible methods of aligning inline frames.
The MARGINWIDTH and MARGINHEIGHT attributes define the number of pixels to
use as the left/right margins and top/bottom margins, respectively, within the
inline frame. The value must be greater than one pixel.
The SCROLLING attribute specifies whether scrollbars are provided for the
inline frame. The default value, auto, generates scrollbars only when
necessary. The value yes gives scrollbars at all times, and the value no
suppresses scrollbars--even when they are needed to see all the content. The
value no should never be used.
ΓòÉΓòÉΓòÉ 1.5.46. IMG - Inline image ΓòÉΓòÉΓòÉ
IMG - Inline Image
Syntax
<IMG>
Attribute Specifications
o SRC= URI (location of image)
o ALT= Text (alternate text)
o LONGDESC= URI (link to long description)
o WIDTH= Length (image width)
o HEIGHT= Length (image height)
o USEMAP= URI (client-side image map)
o ISMAP (server-side image map)
o ALIGN=top|middle|bottom|left|right (image alignment)
o BORDER= Length (link border width)
o HSPACE= Pixels (horizontal gutter)
o VSPACE= Pixels (vertical gutter)
o common attributes
Contents
Empty
Contained in
Inline elements, block-level elements except PRE
The IMG element specifies an inline image. The required SRC attribute
specifies the location of the image. The image can be any format, though
browsers generally only support GIF and JPEG images. Support for the PNG
image format is growing slowly.
The required ALT attribute provides alternate text for those not loading
images. Effective ALT text should generally give the function of the image
rather than a description of the image. For example, ALT="Welcome to XYZ
Corp." would be more appropriate than ALT="XYZ Corp. Logo" for a company's
logo on its welcome page. Good ALT text is crucial to the document's
accessibility for the significant portion of users who do not load images; see
Use of ALT texts in IMGs for a thorough discussion.
The LONGDESC attribute gives the location of a long description of the image.
This attribute should be used to provide a long description of an image where
this would be useful. For example, a painting, graph, or corporate logo could
be given a description so that blind and other text-only users can develop a
mental picture of the image.
The WIDTH and HEIGHT attributes are most useful when they specify the exact
dimensions of the image in pixels. This allows image-loading browsers to
reserve the proper amount of space for the image and continue to render the
rest of the document, thus giving the appearance of a faster-loading page.
Unfortunately, many graphical browsers will use these dimensions when not
loading images, which can cause the ALT text to be cut off if the image is
small or the ALT text is large. In such cases, authors may wish to leave off
the WIDTH and HEIGHT attributes, depending on the importance of the ALT text
and the placement of the image on the page (an image towards the end of the
document without WIDTH and HEIGHT attributes will generally not noticeably
slow the rendering of the page).
Authors can also specify different dimensions for the WIDTH and HEIGHT
attributes, in which case browsers should scale the image. Percentages,
relative to the horizontal or vertical space available (not relative to the
image's natural size) can also be specified, though these are not as widely
supported as pixel lengths. Since browsers typically do a poor job of scaling
images, authors should avoid using WIDTH and HEIGHT for this purpose as much
as possible.
The ALIGN attribute, deprecated in HTML 4.0, specifies the alignment of the
image. The values top, middle, and bottom specify the image's position with
respect to surrounding content on its left and right.
ALIGN=middle aligns the center of the image with the current baseline. To
center the image horizontally on the page, place the image in a centered block,
e.g.,
<H1 ALIGN=center>
<IMG SRC="logo.gif" ALT="Welcome to XYZ Company">
</H1>
The other ALIGN values, left and right, specify a floating image; the image
is placed at the left or right margin and content flows around it. To place
content below the image, use <BR CLEAR=left|right|all> as appropriate.
The vertical-align and float properties of Cascading Style Sheets provide
more flexible methods of aligning images.
The BORDER attribute, deprecated in HTML 4.0, specifies the width of the
image's border. Specifying BORDER=0 will eliminate the border around a linked
image in most browsers, though some allow the user to override this. Authors
should only use BORDER=0 if the image would be clearly recognizable as a link,
or as a method of de-emphasizing a link. For example:
<A HREF="reference/">
<IMG SRC="icon/reference.gif" ALT="" WIDTH=90 HEIGHT=90 BORDER=0>Web Authoring Reference
</A>
The deprecated HSPACE and VSPACE attributes allow an author to suggest
horizontal gutters and vertical gutters, respectively, around the image. The
value must be in pixels and applies to both sides of the image. Style sheets
provide more flexibility in specifying the space around images.
The USEMAP attribute is used with client-side image maps to give the location
of the map definition. While this value may be a full URI--allowing a single
map definition to be applied to multiple pages-- Netscape Navigator will only
find map definitions in the same file, effectively limiting the USEMAP value
to a fragment identifier such as "#map".
The ISMAP attribute is used with server-side image maps. When the ISMAP
attribute is included with a linked image and the user clicks the image, the
image coordinates clicked are sent to the server, from which a location can be
returned. The method of handling the coordinates is server-dependent, but the
NCSA server's method is most common.
Server-side image maps are better supported than client-side image maps, but
almost all browsers today support both methods. Client-side image maps are
generally preferred since they do not require an extra request to the server
(and so are faster), and since they allow a usable menu to be provided to
text-only users. Using both methods in combination is a good approach, since
browsers supporting client-side image maps will use that method while older
browsers will use the server-side image map. An example follows:
<A HREF="/cgi-bin/imagemap/sitemap.map">
<IMG SRC="sitemap.gif" ALT="Site Map" ISMAP USEMAP="#map" WIDTH=100 HEIGHT=100>
</A>
A MAP element named map would have to be included in the same document.
ΓòÉΓòÉΓòÉ 1.5.47. INPUT - Form input ΓòÉΓòÉΓòÉ
INPUT - Form Input
Syntax
<INPUT>
Attribute Specifications
o TYPE=[ text | password | checkbox | radio | submit | reset | file |
hidden | image | button ] (type of input)
o NAME= CDATA (key in submitted form)
o VALUE= CDATA (value of input)
o CHECKED (check radio button or checkbox)
o SIZE= CDATA (suggested number of characters for text input)
o MAXLENGTH= Number (maximum number of characters for text input)
o SRC= URI (source for image)
o ALT= CDATA (alternate text for image input)
o USEMAP= URI (client-side image map)
o ALIGN=[ top | middle | bottom | left | right ] (alignment of image input)
o DISABLED (disable element)
o READONLY (prevent changes)
o ACCEPT= ContentTypes (media types for file upload)
o ACCESSKEY= Character (shortcut key)
o TABINDEX= Number (position in tabbing order)
o ONFOCUS= Script (element received focus)
o ONBLUR= Script (element lost focus)
o ONSELECT= Script (element text selected)
o ONCHANGE= Script (element value changed)
o common attributes
Contents
Empty
Contained in
Block-level elements, inline elements except BUTTON
The INPUT element defines a form control for the user to enter input. While
INPUT is most useful within a FORM, HTML 4.0 allows INPUT in any block-level
or inline element other than BUTTON. However, Netscape Navigator will not
display any INPUT elements outside of a FORM.
When a form is submitted, the current value of each INPUT element within the
FORM is sent to the server as name/value pairs. The INPUT element's NAME
attribute provides the name used. The value sent depends on the type of form
control and on the user's input.
The type of form control defined by INPUT is given by the TYPE attribute.
The default TYPE is text, which provides a single-line text input field. The
VALUE attribute specifies the initial value for the text field. The SIZE and
MAXLENGTH attributes suggest the number of characters and maximum number of
characters, respectively, of the text field.
While the MAXLENGTH attribute can be an effective guide to the user, authors
should not depend on the enforcement of a maximum number of characters by the
client. A user could copy the HTML document, remove the MAXLENGTH attribute,
and submit the form. Thus authors of form handlers should ensure that any
necessary input length checks are repeated on the server-side.
The password input type is a variation on the text type. The only difference
is that the input characters are masked, typically by a series of asterisks, to
protect sensitive information from onlookers. Note, however, that the actual
value is transmitted to the server as clear text, so password inputs do not
provide sufficient security for credit card numbers or other highly sensitive
information.
The following example uses text and password fields with the LABEL element
to bind text labels to the INPUT elements:
<P>
<LABEL ACCESSKEY=U>
User name:
<INPUT TYPE=text NAME=username SIZE=8 MAXLENGTH=8>
</LABEL>
</P>
<P>
<LABEL ACCESSKEY=P>Password:
<INPUT TYPE=password NAME=pw SIZE=12 MAXLENGTH=12>
</LABEL>
</P>
The boolean READONLY attribute, new in HTML 4.0 and poorly supported by
current browsers, prevents the user from editing the content of the text or
password input types. Read-only elements are still submitted with the form.
The DISABLED attribute, which applies to all input types but is also poorly
supported, disables the control. Disabled elements are read-only elements with
the added restrictions that the values are not submitted with the form, the
elements cannot receive focus, and the elements are skipped when navigating the
document by tabbing.
The radio and checkbox input types provide switches that can be turned on and
off by the user. The two types differ in that radio buttons are grouped (by
specifying the same NAME attribute on each INPUT) so that only one radio
button in a group can be selected at any time. Checkboxes can be checked
without changing the state of other checkboxes with the same NAME. The VALUE
attribute, required for radio buttons and checkboxes, gives the value of the
control when it is checked. The boolean CHECKED attribute specifies that the
control is initially checked.
Some browsers require one radio button in a group to be selected at all times.
To ensure that an appropriate default choice is made, authors may wish to
define one of the radio INPUT elements as CHECKED.
In the following example, only one payment method may be selected by the user
since the radio buttons have the same NAME:
<P>Please indicate your method of payment:</P>
<P>
<LABEL ACCESSKEY=C>
<INPUT TYPE=radio NAME="payment_method" VALUE="credit card" CHECKED>
Credit card
</LABEL>
<BR>
<LABEL ACCESSKEY=D>
<INPUT TYPE=radio NAME="payment_method" VALUE="debit card">
Debit card
</LABEL>
<BR>
<LABEL ACCESSKEY=M>
<INPUT TYPE=radio NAME="payment_method" VALUE="money order">
Money order
</LABEL>
</P>
<P>
<LABEL ACCESSKEY=S>
<INPUT TYPE=checkbox NAME="send_receipt" VALUE="yes" CHECKED>
Send receipt by e-mail
</LABEL>
</P>
The file input type creates a field through which users can upload files from
their local computer or network. The VALUE attribute specifies the name of the
initial file, but it is typically ignored by browsers as a security precaution.
The ACCEPT attribute gives a comma-separated list of media types accepted,
allowing the browser to filter out inappropriate files. Current browsers
generally ignore the ACCEPT attribute.
A form that includes a file INPUT must specify METHOD=post and
ENCTYPE="multipart/form-data" in the <FORM> tag. CGI libraries such as
CGI.pm allow simple handling of such forms.
Form-based file upload is unsupported by many currently deployed browsers.
Authors should provide alternative methods of input where possible.
The following example allows the user to upload an HTML document for
validation:
<FORM METHOD=post
ACTION="/cgi-bin/validate.cgi"
ENCTYPE="multipart/form-data">
<P>Select an HTML document to upload
and validate. If your browser does not
support form-based file upload, use one
of our <A HREF="methods.html">alternate
methods of validation</A>.</P>
<P><INPUT TYPE=file NAME="html_file"
ACCEPT="text/html"></P>
<P><INPUT TYPE=submit VALUE="Validate
it!"></P>
</FORM>
The hidden input type allows authors to include form data without having it
rendered to the user. This is particularly useful in form applications that
span several HTML documents; user input can be carried from form to form by
hidden INPUTs. Some generalized CGI scripts use hidden INPUTs to define
variables for the script, as in the following example, which defines a
recipient and subject for the e-mailed contents of a form:
<INPUT TYPE=hidden NAME=recipient
VALUE="liam@htmlhelp.com">
<INPUT TYPE=hidden NAME=subject
VALUE="Feedback on your HTML Reference">
Note that the fields are "hidden" in the sense that they are not rendered by
the browser. Anyone can still view the HTML document's source to find the
"hidden" fields.
The TYPE value reset defines a button by which the user can reset the form to
its initial values. The optional VALUE attribute of a reset button overrides
the browser's default text for the button.
The submit input type defines a button for submitting the form. As with
reset, the optional VALUE attribute provides the text of the button. The
presence of the NAME attribute will cause the browser to send a name/value pair
for the submit button if it is used to submit the form. This allows authors to
provide multiple submit buttons and have the form handler take a different
action depending on the submit button used.
The image input type specifies a graphical submit button. The SRC attribute
must be included to specify the URI of the image. The ALT attribute should
be used to give replacement text for those not loading images. ALT is a new
addition in HTML 4.0; many browsers rely on either the NAME or VALUE
attribute as alternate text, so authors should use all three attributes for the
same purpose where possible. The topic of graphical submit buttons for text
users is discussed in detail in the article INPUT TYPE=IMAGE for text users?.
When the graphical submit button is clicked, the coordinates of the click are
sent with the form submission as name.x=x-value and name.y=y-value where name
is the value of the NAME attribute, x-value is the click's pixels from the
left of the image, and y-value is the click's pixels from the top of the
image. The USEMAP attribute combined with TYPE=image defines a client-side
image map that can be used with client-side scripting, but this method is
poorly supported. The USEMAP attribute gives the URI of the defining MAP.
The deprecated ALIGN attribute specifies the alignment of the graphical
submit button. The values top, middle, and bottom specify the button's
position with respect to surrounding content on its left and right. The values
left and right specify a floating button; the image is placed at the left or
right margin and content flows around it. To place content below the button,
use <BR CLEAR=left|right|all> as appropriate.
The vertical-align and float properties of Cascading Style Sheets provide
more flexible methods of aligning buttons.
The input type button specifies a push button for use with client-side
scripting. The VALUE attribute gives the text label of the button. The
ONCLICK attribute is typically used to define the action taken when the button
is activated. An example follows:
<INPUT TYPE=button VALUE="Hide non-strict attributes"
ID=toggler ONCLICK="toggle()">
In this example, the toggle() function, which would be defined earlier in a
SCRIPT element, will be executed when the button is clicked. Since the button
is only useful with client-side scripting enabled, authors should usually
output the <INPUT TYPE=button> tag using the scripting language to avoid
providing a non-functioning button to some users. A more complete version of
the previous example would thus be as follows:
<SCRIPT TYPE="text/javascript">
<!--
document.write("<INPUT TYPE=button VALUE=\"Hide non-strict attributes\""
+ "ID=toggler ONCLICK=\"toggle()\">");
// -->
</script>
The BUTTON element allows richer labels for submit, reset, and push buttons,
but a lack of browser support makes INPUT a more reliable choice at this time.
The ACCESSKEY and TABINDEX attributes apply to all input types except hidden.
ACCESSKEY specifies a single Unicode character as a shortcut key for giving
focus to the form control. Authors can set the access key on the INPUT
element or the LABEL element associated with it. Entities (e.g. é)
may be used as the ACCESSKEY value.
The TABINDEX attribute specifies a number between 0 and 32767 to indicate the
tabbing order of the element. A form control with TABINDEX=0 or no TABINDEX
attribute will be visited after any elements with a positive TABINDEX. Among
positive TABINDEX values, the lower number receives focus first. In the case
of a tie, the element appearing first in the HTML document takes precedence.
The INPUT element also takes a number of attributes to specify client-side
scripting actions for various events. In addition to the core events common
to most elements, INPUT accepts the following event attributes:
o ONFOCUS, when the element receives focus;
o ONBLUR, when the element loses focus;
o ONSELECT, when text in an input of type text or password is selected;
o ONCHANGE, when the element loses focus and its value has changed since it
received focus.
ΓòÉΓòÉΓòÉ 1.5.48. INS - Inserted text ΓòÉΓòÉΓòÉ
INS - Inserted Text
Syntax
<INS>...</INS>
Attribute Specifications
o CITE= URI (reason for insertion)
o DATETIME= Datetime (date and time of insertion)
o common attributes
Contents
Inline elements, block-level elements
Contained in
Inline elements, block-level elements
The INS element contains content that has been inserted. This element is
useful in marking changes from one version of a document to the next. Through
style sheets, authors can suggest an appropriate rendering, such as rendering
the inserted content in italics, a different color, or a different voice.
INS may be used as either a block-level element or an inline element. If
used as an inline element (e.g., within a P), then INS may not contain any
block-level elements.
The optional CITE attribute of INS gives a URI with information on why the
content was inserted. A brief explanation for the insertion can be given with
the TITLE attribute, which may be rendered as a "tooltip" by some browsers.
The optional DATETIME attribute specifies the date and time of the insertion.
The value is case-sensitive and of the form YYYY-MM-DDThh:mm:ssTZD. See the
values section for a full explanation of this format.
An example follows:
<P>The CENTER element defines a block whose
contents are centered horizontally on visual browsers.
<INS CITE="http://www.w3.org/TR/REC-html40/appendix/changes.html#h-A.1.2"
DATETIME="1997-12-19T00:00:00-05:00">
Note that CENTER is deprecated in HTML 4.0.
</INS></P>
ΓòÉΓòÉΓòÉ 1.5.49. ISINDEX - Input prompt ΓòÉΓòÉΓòÉ
ISINDEX - Input Prompt
Syntax
<ISINDEX>
Attribute Specifications
o PROMPT= Text (Prompt message)
o core attributes
o internationalization attributes
Contents
Empty
Contained in
APPLET, BLOCKQUOTE, BODY, CENTER, DD, DEL, DIV, FIELDSET, FORM, HEAD,
IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The ISINDEX element defines a single-line text input. The label of the input
field is specified using the element's PROMPT attribute. ISINDEX is
deprecated in HTML 4.0 in favor of the INPUT element.
The ISINDEX element is equivalent to a FORM with a single INPUT of type
text, a METHOD of get, and an ACTION pointing to the URI of the document
containing the ISINDEX element.
ΓòÉΓòÉΓòÉ 1.5.50. KBD - Text to be input ΓòÉΓòÉΓòÉ
KBD - Text to be Input
Syntax
<KBD>...</KBD>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The KBD element denotes text to be entered by the user. Visual browsers
typically render KBD as monospaced text, but authors can suggest a rendering
using style sheets. Since KBD is a structural element, it carries meaning,
making it preferable to font style elements such as TT when marking up text
to be entered by the user.
Example:
<P>If the question does not apply to you, enter
<KBD>N/A</KBD>.
ΓòÉΓòÉΓòÉ 1.5.51. LABEL - Form field label ΓòÉΓòÉΓòÉ
LABEL - Form Field Label
Syntax
<LABEL>...</LABEL>
Attribute Specifications
o FOR= IDREF (associated form field)
o ACCESSKEY= Character (shortcut key)
o ONFOCUS= Script (element received focus)
o ONBLUR= Script (element lost focus)
o common attributes
Contents
Inline elements except LABEL
Contained in
Block-level elements, inline elements except BUTTON
The LABEL element associates a label with a form control. By associating
labels with form controls, authors give important hints to users of speech
browsers while also allowing visual browsers to duplicate common GUI features
(e.g., the ability to click on a text label to select a radio button or
checkbox).
Each LABEL element is associated with exactly one form control. The element's
content is the label of the form control and may include inline elements such
as IMG and STRONG.
The FOR attribute explicitly specifies the control associated with the LABEL.
The value of the FOR attribute must match the value of the associated form
control's ID attribute. In the absence of the FOR attribute, the LABEL
must contain the associated form control. This method of implicit association
is convenient in many cases, but not an option when the form control and its
label are in different table cells, paragraphs, or divisions. The following
example illustrates both explicit and implicit label associations:
<TABLE>
<TR>
<TD>
<LABEL FOR=user ACCESSKEY=U>User</LABEL>
</TD>
<TD>
<SELECT NAME=user ID=user>
<OPTION>Jean</OPTION>
<OPTION>Kim</OPTION>
<OPTION>Brian</OPTION>
</SELECT>
</TD>
</TR>
<TR>
<TD><LABEL FOR=passwd ACCESSKEY=P>Password</LABEL></TD>
<TD><INPUT TYPE=password NAME=password ID=passwd></TD>
</TR>
</TABLE>
<P>
<LABEL ACCESSKEY=S> <INPUT TYPE=checkbox NAME=save VALUE=yes> Save user
name and password in a cookie </LABEL> </P> <P> <LABEL
ACCESSKEY=C> Comments to post: <TEXTAREA NAME=comments ROWS=8
COLS=50></TEXTAREA> </LABEL> </P>
The ACCESSKEY attribute, used throughout the preceding example, specifies a
single Unicode character as a shortcut key for giving focus to the LABEL, which
passes the focus on to the associated form control. Entities (e.g. é)
may be used as the ACCESSKEY value.
The LABEL element also takes a number of attributes to specify client-side
scripting actions for various events. In addition to the core events common
to most elements, LABEL accepts the following event attributes:
o ONFOCUS, when the element receives focus;
o ONBLUR, when the element loses focus.
ΓòÉΓòÉΓòÉ 1.5.52. LEGEND - Fieldset caption ΓòÉΓòÉΓòÉ
LEGEND - Fieldset Caption
Syntax
<LEGEND>...</LEGEND>
Attribute Specifications
o ACCESSKEY= Character (shortcut key)
o ALIGN=[ top | bottom | left | right ] (alignment relative to fieldset)
o common attributes
Contents
Inline elements
Contained in
FIELDSET
The LEGEND element defines a caption for form controls grouped by the
FIELDSET element. The LEGEND element must be at the start of a FIELDSET,
before any other elements.
While the LEGEND element is not widely supported by current browsers, it can
still be used safely if a block-level element immediately follows the LEGEND.
Combined with careful use of FIELDSET, this will cause non-supporting browsers
to render the caption as its own paragraph. Elements such as STRONG, B, and
BIG could also be used to help express the meaning of LEGEND to
non-supporting browsers.
An example follows:
<FIELDSET>
<LEGEND ACCESSKEY=C>Credit Card Information</LEGEND>
<P>
<LABEL ACCESSKEY=V>
<INPUT TYPE=radio NAME=card VALUE=visa> Visa
</LABEL>
<LABEL ACCESSKEY=M>
<INPUT TYPE=radio NAME=card VALUE=mc> MasterCard
</LABEL>
<BR>
<LABEL ACCESSKEY=N>
Number: <INPUT TYPE=text NAME=number>
</LABEL>
<BR>
<LABEL ACCESSKEY=E>
Expiry: <INPUT TYPE=text NAME=expiry>
</LABEL>
</P>
</FIELDSET>
LEGEND's ACCESSKEY attribute, used throughout the preceding example, specifies
a single Unicode character as a shortcut key for giving focus to the LEGEND,
allowing the user to quickly jump to a group of form controls. Entities (e.g.
é) may be used as the ACCESSKEY value.
The deprecated ALIGN attribute of LEGEND suggests where the caption should
be positioned relative to the FIELDSET on visual browsers. Possible values
are top, bottom, left, and right. While ALIGN is deprecated, no alternative
currently exists in Cascading Style Sheets.
ΓòÉΓòÉΓòÉ 1.5.53. LI - List item ΓòÉΓòÉΓòÉ
LI - List Item
Syntax
<LI>...</LI>
Attribute Specifications
o TYPE=[ disc | square | circle | 1 | a | A | i | I ] (style of list item
marker)
o VALUE= Number (number in sequence)
o common attributes
Contents
Inline elements, block-level elements (except for LIs used within
DIR and MENU, which do not allow block-level elements)
Contained in
OL, UL, DIR, MENU
The LI element defines a list item. The element must be contained within
DIR, MENU, OL or UL.
Unless used with the deprecated MENU or DIR elements, LI may contain
block-level elements, including H2, TABLE, UL, and OL. This allows OL and
UL to be nested, as in the following example:
<UL>
<LI>
<H2>HTML Document Type Definitions</H2>
<UL>
<LI><A HREF="html.dtd">HTML 2.0</A></LI>
<LI><A HREF="HTML32.dtd">HTML 3.2</A></LI>
<LI><A HREF="strict.dtd">HTML 4.0 Strict</A></LI>
</UL>
</LI>
<LI>
<H2>SGML Character Entity References</H2>
<UL>
<LI><A HREF="HTMLlat1.ent">Latin-1 Entities</A></LI>
<LI><A HREF="HTMLsymbol.ent">Symbols and Greek Letters</A></LI>
<LI><A HREF="HTMLspecial.ent">Other Special Characters</A></LI>
</UL>
</LI>
</UL>
When used with MENU and DIR, LI may not contain block-level elements, and
lists cannot be nested.
The deprecated TYPE attribute of LI suggests the rendering of the list item
marker. Possible values are as follows:
o Case-insensitive values for LI within a UL, DIR, or MENU:
- disc (a filled-in circle)
- square (a square outline)
- circle (a circle outline)
o Case-sensitive values for LI within an OL:
- 1 (decimal numbers: 1, 2, 3, 4, 5, ...)
- a (lowercase alphabetic: a, b, c, d, e, ...)
- A (uppercase alphabetic: A, B, C, D, E, ...)
- i (lowercase Roman numerals: i, ii, iii, iv, v, ...)
- I (uppercase Roman numerals: I, II, III, IV, V, ...)
Style sheets provide greater flexibility in suggesting list item styles. The
list-style property of CSS includes the added abilities to suppress list item
markers, use images as markers, and more.
LI's VALUE attribute specifies the number of the list item when used with an
OL. The number must be given as an integer, though the list item marker may be
rendered in another form (for example, as a Roman numeral). Any LI element
following in the same list will take its default sequence number based on the
first preceding VALUE attribute. VALUE is deprecated in HTML 4.0, but no
substitute currently exists in CSS.
ΓòÉΓòÉΓòÉ 1.5.54. LINK - Document relationship ΓòÉΓòÉΓòÉ
LINK - Document Relationship
Syntax
<LINK>
Attribute Specifications
o REL= LinkTypes (relationship to link)
o REV= LinkTypes (relationship from link)
o HREF= URI (hypertext reference)
o TYPE= ContentType (content-type of link)
o TARGET= FrameTarget (frame to render link in)
o MEDIA= MediaDesc (media appropriate for link)
o HREFLANG= LanguageCode (language of link)
o CHARSET= Charset (character encoding of link)
o common attributes
Contents
Empty
Contained in
HEAD
The LINK element defines document relationships. Any number of LINK elements
may be contained in the HEAD of a document. Many browsers lack support for
LINK, so authors should not depend on the browser making the links available to
the user.
The REL and REV attributes define the nature of the relationship between the
documents and the linked resource. REL defines a link relationship from the
current document to the linked resource while REV defines a relationship in
the opposite direction. For example,
<LINK REL=Glossary HREF="foo.html">
indicates that foo.html is a glossary for the current document while
<LINK REV=Subsection HREF="bar.html">
indicates that the current document is a subsection of bar.html. The value of
the REL and REV attributes is a space-separated list of link types.
Commonly used relationships include the next or previous document in a
sequence, the starting page in a collection of documents, a document with
copyright information, and information about the author. A document could
define these relationships as follows:
<LINK REL=Prev HREF="base.html" TITLE="BASE - Document Base URI">
<LINK REL=Next HREF="meta.html"
TITLE="META - Metadata">
<LINK REL=Start HREF=""
TITLE="HTML 4.0 Reference">
<LINK REL=Copyright HREF="/copyright.html"
TITLE="Copyright Notice">
<LINK REV=Made HREF="mailto:liam@htmlhelp.com"
TITLE="HTML 4.0 Reference Feedback">
While the value of REL and REV is case-insensitive, the Lynx browser renders
the relationship exactly as given by the author. Authors should therefore be
consistent in their case, and may wish to capitalize the first letter while
using lowercase for the rest.
Authors can also use the LINK element to apply an external style sheet.
REL=StyleSheet specifies a persistent or preferred style while REL="Alternate
StyleSheet" defines an alternate style. A persistent style is one that is
always applied when style sheets are enabled. The absence of the TITLE
attribute indicates a persistent style.
A preferred style is one that is automatically applied. The combination of
REL=StyleSheet and a TITLE attribute specifies a preferred style. Authors
cannot specify more than one preferred style.
An alternate style is indicated by REL="Alternate StyleSheet". The user could
choose to replace the preferred style sheet with an alternate one, though
current browsers generally lack the ability to choose alternate styles.
A single style may also be given through multiple style sheets:
<LINK REL=StyleSheet HREF="basics.css"
TITLE="Contemporary" TYPE="text/css">
<LINK REL=StyleSheet HREF="tables.css"
TITLE="Contemporary" TYPE="text/css">
<LINK REL=StyleSheet HREF="forms.css"
TITLE="Contemporary" TYPE="text/css">
In this example, three style sheets are combined into one "Contemporary" style
that is applied as a preferred style sheet. To combine multiple style sheets
into a single style, each style sheet's LINK must use the same TITLE.
LINK's MEDIA attribute specifies the media for which the linked resource is
designed. With REL=StyleSheet, this allows authors to restrict a style sheet
to certain output devices, such as printers or aural browsers. The attribute's
value is a comma-separated list of media descriptors. The following media
descriptors are defined in HTML 4.0 and are case-sensitive:
o screen (the default), for non-paged computer screens;
o tty, for fixed-pitch character grid displays (such as the display used by
Lynx);
o tv, for television-type devices with low resolution and limited
scrollability;
o projection, for projectors;
o handheld, for handheld devices (characterized by a small, monochrome display
and limited bandwidth);
o print, for output to a printer;
o braille, for braille tactile feedback devices;
o aural, for speech synthesizers;
o all, for all devices.
Netscape Navigator 4.x incorrectly ignores any style sheet linked with a MEDIA
value other than screen. For example, MEDIA="screen, projection" will cause
the style sheet to be ignored by Navigator 4.x, even if the presentation device
is a computer screen. Navigator 4.x also ignores style sheets declared with
MEDIA=all. Most other browsers ignore the MEDIA attribute.
The optional HREFLANG and CHARSET attributes of LINK give the language and
character encoding, respectively, of the link. The language should be
specified according to RFC 1766; examples include en for English, en-US for
American English, and ja for Japanese. Examples of character encodings
include ISO-8859-1, SHIFT_JIS, and UTF-8.
The Alternate link relationship defines an alternate version of the document.
Translations of a page can be identified by using REL=Alternate along with the
HREFLANG attribute. Versions of the page tailored for specific media can be
provided by combining REL=Alternate with the MEDIA attribute. Some examples
follow:
<LINK REL=Alternate
HREF="index.fr.html"
HREFLANG=fr
LANG=fr
TITLE="Version franчaise">
<LINK REL=Alternate
HREF="index.ja.html"
HREFLANG=ja
CHARSET="SHIFT_JIS"
TITLE="Japanese version">
<LINK REL=Alternate
HREF="/distribution/html40.pdf"
TYPE="application/pdf"
MEDIA=print
TITLE="PDF version">
Note that the LANG and DIR attributes apply to the text of the TITLE
attribute, not to the content of the link.
The TARGET attribute is used with frames to specify in which frame the link
should be rendered. If no frame with such a name exists, the link is rendered
in a new window unless overridden by the user. Special frame names begin with
an underscore:
o _blank renders the link in a new, unnamed window
o _self renders the link in the current frame (useful for overriding a BASE
TARGET)
o _parent renders the link in the immediate FRAMESET parent
o _top renders the link in the full, unframed window
ΓòÉΓòÉΓòÉ 1.5.55. MAP - Image map ΓòÉΓòÉΓòÉ
MAP - Image Map
Syntax
<MAP>...</MAP>
Attribute Specifications
o NAME= CDATA (name of map)
o common attributes
Contents
One or more block-level elements or one or more AREA elements
Contained in
Inline elements, block-level elements
The MAP element defines a client-side image map for use with an IMG or
OBJECT. MAP's required NAME attribute is used as an anchor for the USEMAP
attribute of the IMG or OBJECT. While a MAP element can define image maps
embedded in other files, browsers typically only support client-side image maps
with the MAP in the same file as the image.
MAP was originally defined to take one or more AREA elements that specified
the coordinates of a clickable region on the image. An example follows:
<MAP NAME=mymap>
<AREA HREF="/reference/" ALT="HTML and
CSS Reference" COORDS="5,5,95,195">
<AREA HREF="/design/" ALT="Design
Guide" COORDS="105,5,195,195">
<AREA HREF="/tools/" ALT="Tools"
COORDS="205,5,295,195">
</MAP>
<IMG SRC="sitemap.gif" ALT="Site map"
USEMAP="#mymap" WIDTH=300 HEIGHT=200>
HTML 4.0 extends the MAP element to take one or more block-level elements as
an alternative to using AREA elements. Combined with the OBJECT element,
this allows rich alternative content for those not loading images. However,
due to poor and buggy browser support for OBJECT, client-side image maps
through the IMG element are more reliable.
When MAP is given within an OBJECT, its contents are not rendered on
image-loading browsers. MAP may also be used outside the OBJECT element so
that its contents are rendered.
The following example gives two images, one an alternate if the first type of
image is not supported. The images share a single image map definition, which
is included within the OBJECT element. The MAP element contains a menu of
links to be rendered on browsers not loading images.
<OBJECT DATA="sitemap.png"
USEMAP="#map" TYPE="image/png"
TITLE="Site map" WIDTH=300 HEIGHT=200>
<OBJECT DATA="sitemap.gif"
USEMAP="#map" TYPE="image/gif"
TITLE="Site map" WIDTH=300 HEIGHT=200>
<MAP NAME=map>
<UL>
<LI><A HREF="/reference/"
COORDS="5,5,95,195">HTML and CSS Reference</A>
</LI>
<LI><A HREF="/design/"
COORDS="105,5,195,195">Design
Guide</A>
</LI>
<LI><A HREF="/tools/index.html"
COORDS="205,5,295,195">Tools</A>
</LI>
</UL>
</MAP>
</OBJECT>
</OBJECT>
ΓòÉΓòÉΓòÉ 1.5.56. MENU - Menu list ΓòÉΓòÉΓòÉ
MENU - Menu List
Syntax
<MENU>...</MENU>
Attribute Specifications
o COMPACT (compact display)
o common attributes
Contents
One or more LI elements that cannot contain block-level elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The MENU element defines a menu list. The element contains one or more LI
elements that define the actual items of the list. The LI elements must not
contain block-level elements, which prevents MENUs from being nested.
The COMPACT attribute suggests that visual browsers render the list compactly,
perhaps with reduced spacing between items. This attribute is not well
supported among browsers.
MENU is deprecated in HTML 4.0 in favor of UL.
ΓòÉΓòÉΓòÉ 1.5.57. META - Metadata ΓòÉΓòÉΓòÉ
META - Metadata
Syntax
<META>
Attribute Specifications
o NAME= Name (property name)
o HTTP-EQUIV= Name (HTTP response header name)
o CONTENT= CDATA (associated data)
o SCHEME= CDATA (form of data)
o internationalization attributes (for the CONTENT)
Contents
Empty
Contained in
HEAD
The META element provides metadata such as a document's keywords,
description, and author. Any number of META elements may be contained in the
HEAD of a document.
META's NAME attribute provides a property name while the CONTENT attribute
gives the corresponding value. The CONTENT attribute value may contain text
and entities, but it may not contain HTML tags.
The optional SCHEME attribute gives the format of the property value. For
example, a date property may require SCHEME="Month-Day-Year" to disambiguate
the date from other formats such as SCHEME="Day-Month-Year".
There is no standard list of META properties, so authors may define whatever
metadata they like. The following example defines the author of the document:
<META NAME=author CONTENT="Liam Quinn">
Some search engines use keywords and description properties, giving extra
weight to a document's keywords and providing its description with the link to
the document. Example:
<META NAME="description"
CONTENT="A description of HTML 4.0's META element for metadata.">
<META NAME="keywords"
CONTENT="META, meta element, metadata, metainformation, meta
data, meta information, keywords, description,
refresh, HyperText Markup Language, HTML, HTML4,
HTML 4.0, Web Design Group, WDG, <meta>
tag, <META> tag">
To avoid being truncated by search engines, the description should be brief--no
more than 200 characters. Keywords are separated by commas and may be
considered case sensitive by search engines. If the same keywords are repeated
too often in the META element, some search engines will not index the
document. Search engines typically only process the first 1000 characters of
the keywords list.
Some search engines also support the robots property for indicating whether a
document should be indexed and whether its links should be followed. The
associated CONTENT value is a comma-separated list of case-insensitive
directives:
o index specifies that the page should be indexed while noindex specifies
that it should not be indexed;
o follow specifies that the page's links should be followed while nofollow
specifies that they should not be followed;
o all is equivalent to index,follow (the default value);
o none is equivalent to noindex,nofollow.
For example, the following META element tells search engines and other robots
not to index the page but to follow links on it:
<META NAME=robots CONTENT="noindex,follow">
Few search engines support the robots property at this time. For greater
compliance by robots, authors should use the Robots Exclusion Protocol if
possible.
The HTTP-EQUIV attribute may be used in place of the NAME attribute to
indicate that the property is an HTTP header. Some servers will send the HTTP
header specified in the META element, and browsers often recognize the header
even when it is not sent by the server. Examples:
<META HTTP-EQUIV=Expires
CONTENT="Sun, 22 Mar 1998 16:18:35 GMT">
sets the expiry date of the document.
<META
HTTP-EQUIV="Content-Script-Type" CONTENT="text/javascript">
sets the client-side scripting language for inline scripts to JavaScript.
<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">
sets the style language for inline styles to CSS.
<META HTTP-EQUIV="Content-Type"
CONTENT="text/html; charset=SHIFT_JIS">
sets the character encoding for the document to SHIFT_JIS (a Japanese
encoding). Note that using META for this purpose rather than a true HTTP
header causes some browsers to redraw the page after initially displaying it.
<META HTTP-EQUIV=Refresh CONTENT="10;
URL=http://www.htmlhelp.com/">
tells the browser to load http://www.htmlhelp.com/ 10 seconds after the current
document has finished loading. Not all browsers support this, so authors
should provide an alternate means of moving to the new page where necessary.
The Refresh header is sometimes used for "splash screens" or when a page has
moved, but the technique is not very effective since users may not even be
looking at the window that is to be refreshed and since it messes up the user's
history on many browsers. Some search engines penalize pages that use a
Refresh of a few seconds or less.
ΓòÉΓòÉΓòÉ 1.5.58. NOFRAMES - Frames alternate content ΓòÉΓòÉΓòÉ
NOFRAMES - Frames Alternate Content
Syntax
<NOFRAMES>...<NOFRAMES>
Attribute Specifications
o common attributes
Contents
o In HTML 4.0 Transitional: inline elements, block-level elements
o In HTML 4.0 Frameset: one BODY element that must not contain any
NOFRAMES elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, FRAMESET, IFRAME, INS, LI, MAP, NOSCRIPT, OBJECT, TD, TH
The NOFRAMES element contains content that should only be rendered when frames
are not displayed. NOFRAMES is typically used in a Frameset document to
provide alternate content for browsers that do not support frames or have
frames disabled.
When used within a FRAMESET, NOFRAMES must contain a BODY element. There
must not be any NOFRAMES elements contained within this BODY element.
A meaningful NOFRAMES element should always be provided in a Frameset document
and should at the very least contain links to the main frame or frames.
NOFRAMES should not contain a message telling the user to upgrade his or her
browser. Some browsers support frames but allow the user to disable them.
Various methods of automatically creating non-frames content exist. See Frames
design guidelines: automatic no-frames content for more details.
An example follows:
<FRAMESET ROWS="*,100">
<FRAMESET COLS="40%,*">
<FRAME NAME="Menu" SRC="nav.html" TITLE="Menu">
<FRAME NAME="Content" SRC="main.html" TITLE="Content">
</FRAMESET>
<FRAME NAME="Ad" SRC="ad.html" TITLE="Advertisement">
<NOFRAMES>
<BODY>
<H1>Table of Contents</H1>
<UL>
<LI>
<A HREF="reference/html40/">HTML 4.0 Reference</A>
</LI>
<LI>
<A HREF="reference/wilbur/">HTML 3.2 Reference</A>
</LI>
<LI>
<A HREF="reference/css/">CSS Guide</A>
</LI>
</UL>
<P>
<IMG SRC="ad.gif" ALT="Ad: Does your bank charge too much?">
</P>
</BODY>
</NOFRAMES>
</FRAMESET>
In HTML 4.0 Transitional, the NOFRAMES element is also permitted within most
block-level elements. This allows authors to include content, such as
navigation aids, that should only be displayed if the document is not being
viewed within a frameset. Such use helps to ensure that a frame could stand on
its own if bookmarked or accessed through a search engine while not burdening
the frames user with duplicate content. However, most browsers do not support
this use of NOFRAMES and will always display the content.
ΓòÉΓòÉΓòÉ 1.5.59. NOSCRIPT - Alternate script content ΓòÉΓòÉΓòÉ
NOSCRIPT - Non-script Content
Syntax
<NOSCRIPT>...</NOSCRIPT>
Attribute Specifications
o common attributes
Contents
Block-level elements, inline elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The NOSCRIPT element provides alternate content for a client-side script that
was not executed. A script will fail to execute if the browser does not
support the scripting language or if the user has disabled client-side
scripting. NOSCRIPT should follow the SCRIPT element for which it provides
alternate content.
Note that most browsers will fail to render the contents of NOSCRIPT if the
scripting language is not supported and the user has enabled client-side
scripting. Most browsers will only render NOSCRIPT when the user has disabled
client-side scripting.
Also note that Netscape Navigator 2.x supports JavaScript 1.0 but still
renders all NOSCRIPT content.
Since client-side scripts usually provide dynamic interactivity that cannot be
replaced by static content, the NOSCRIPT element is generally not useful.
Authors should try to use client-side scripts as optional enhancements that are
not integral components of the Web page. In the case of form validation, any
error checking done by the client-side script should be repeated by the CGI
script or Java servlet that handles the submission at the server.
ΓòÉΓòÉΓòÉ 1.5.60. OBJECT - Object ΓòÉΓòÉΓòÉ
OBJECT - Embedded Object
Syntax
<OBJECT>...</OBJECT>
Attribute Specifications
o DATA= URI (object data)
o CLASSID= URI (location of implementation)
o ARCHIVE= CDATA (archive files)
o CODEBASE= URI (base URI for CLASSID, DATA, ARCHIVE)
o WIDTH= Length (object width)
o HEIGHT= Length (object height)
o NAME= CDATA (name for form submission)
o USEMAP= URI (client-side image map)
o TYPE= ContentType (content-type of object)
o CODETYPE= ContentType (content-type of code)
o STANDBY= Text (message to show while loading)
o TABINDEX= NUMBER (position in tabbing order)
o DECLARE (do not instantiate object)
o ALIGN=[ top | middle | bottom | left | right ] (object alignment)
o BORDER= Length (link border width)
o HSPACE= Pixels (horizontal gutter)
o VSPACE= Pixels (vertical gutter)
o common attributes
Contents
PARAM elements followed by block-level elements and/or inline
elements
Contained in
HEAD, inline elements, block-level elements except PRE
The OBJECT element is used to include objects such as images, videos, Java
applets, and VRML worlds. OBJECT is intended to replace the more specific
IMG and APPLET elements, as well as the proprietary EMBED and BGSOUND
elements, though a lack of browser support and severe bugs in supporting
browsers make the other elements a better choice for the time being.
OBJECT's DATA attribute specifies the URI of the embedded object. Relative
URIs are interpreted with respect to the CODEBASE attribute if it is given.
The WIDTH and HEIGHT attributes define the dimensions of the object. The
value may be given in pixels or as a percentage of the parent element's width
or height. Most browsers require the WIDTH and HEIGHT attributes for all
objects embedded using OBJECT.
The CLASSID may be used to specify an implementation for the object. Java
applets, Python applets, and ActiveX controls all provide implementations for
the embedded object, and so are specified with the CLASSID attribute, as in
the following example:
<OBJECT CLASSID="yahtzee.py"
CODETYPE="application/x-python" STANDBY="Ready to play
Yahtzee?" TITLE="My Yahtzee Game">
<OBJECT CLASSID="java:Yahtzee.class"
CODETYPE="application/java" WIDTH=400 HEIGHT=250 STANDBY="Ready to play
Yahtzee?" TITLE="My Yahtzee Game">
<OBJECT DATA="yahtzee.gif" TYPE="image/gif" TITLE="A
Yahtzee animation" WIDTH=200 HEIGHT=100>
Yahtzee is my <EM>favorite</EM> game!
</OBJECT>
</OBJECT>
</OBJECT>
This example also demonstrates the use of alternate content for browsers that
cannot display the embedded object. In the example, a Yahtzee game written in
Python is used if the browser supports it. A Java version is provided as an
alternate for browsers that do not support Python applets. An image is given
for browsers that cannot show the Java or Python applets, and plain text is
used as a final alternate if images are not loaded. Note that OBJECT is
backwards compatible with pre-HTML 4.0 browsers since they will ignore the
<OBJECT> tags and render the innermost alternate content (the text in the
example).
The preceding example also makes use of the TYPE and CODETYPE attributes to
allow browsers to avoid requesting a file that they cannot render. The TYPE
attribute specifies the media type of the resource referenced by the DATA
attribute while the CODETYPE attribute specifies the media type of the CLASSID
data.
The STANDBY attribute is also utilized in the example. This attribute
provides short text to display while the object is loading.
The ARCHIVE attribute can specify a space-separated list of archived files
(either absolute URIs or URIs relative to the CODEBASE), allowing the browser
to download many files with a single connection and hence decreasing the total
download time. The standard archive format for Java files is JAR. JAR files
can be created with the jar tool included with the Java Development Kit 1.1
and up.
The DECLARE attribute makes the object a declaration that is not immediately
instantiated. This allows the object to be instantiated from a link, button,
or object later in the same document. The ID attribute must be used with
declared objects as an identifier for the instantiating element. For example:
<OBJECT DECLARE ID=yahtzee CLASSID="java:Yahtzee.class"
CODETYPE="application/java" WIDTH=400 HEIGHT=250
TITLE="My Yahtzee Game">
<IMG SRC="yahtzee.gif" ALT="You get the dice!"
TITLE="Yahtzee animation">
</OBJECT>
...
<P>Ready to <A HREF="#yahtzee">play Yahtzee</A>?</P>
The OBJECT element may contain PARAM elements--before any other content--to
provide run-time initialization data. The following example embeds a video,
with an audio clip for alternate content, and includes parameters commonly
understood by audio/video plug-ins. Note the placement of PARAM elements
before alternate content.
<OBJECT DATA="mlk.mov" TYPE="video/quicktime"
TITLE="Martin Luther King's "I Have a Dream"
speech" WIDTH=150 HEIGHT=150>
<PARAM NAME=pluginspage
VALUE="http://quicktime.apple.com/">
<PARAM NAME=autoplay VALUE=true>
<OBJECT DATA="mlk.wav" TYPE="audio/x-wav" TITLE="Martin
Luther King's "I Have a Dream" speech">
<PARAM NAME=autostart VALUE=true>
<PARAM NAME=hidden VALUE=true>
<A HREF="mlk.html">Full text of Martin Luther King's "I
Have a Dream" speech</A>
</OBJECT>
</OBJECT>
The USEMAP attribute can be used with OBJECT to embed a clickable image where
different coordinates have different link destinations. Image maps via the
IMG element are better supported, but OBJECT-based image maps allow a full
textual alternative for browsers not loading images. The USEMAP attribute
points to a MAP element whose contents define the links of the various
coordinates. The MAP may be included within the OBJECT, in which case its
contents are not rendered on image-loading browsers, or it may be given outside
the OBJECT element so that its contents are rendered.
The following example gives two images, one an alternate if the first type of
image is not supported. The images share a single image map definition, which
is included within the OBJECT element. The MAP element contains a menu of
links to be rendered on browsers not loading images.
<OBJECT DATA="sitemap.png" USEMAP="#map" TYPE="image/png"
TITLE="Site map" WIDTH=300 HEIGHT=200>
<OBJECT DATA="sitemap.gif" USEMAP="#map" TYPE="image/gif"
TITLE="Site map" WIDTH=300 HEIGHT=200>
<MAP NAME=map>
<UL>
<LI><A HREF="/reference/" COORDS="5,5,95,195">HTML and
CSS Reference</A></LI>
<LI><A HREF="/design/" COORDS="105,5,195,195">Design
Guide</A></LI>
<LI><A HREF="/tools/index.html"
COORDS="205,5,295,195">Tools</A></LI>
</UL>
</MAP>
</OBJECT>
</OBJECT>
The TABINDEX attribute specifies a number between 0 and 32767 to indicate the
tabbing order of the element. An object with TABINDEX=0 or no TABINDEX
attribute will be visited after any elements with a positive TABINDEX. Among
positive TABINDEX values, the lower number receives focus first. In the case
of a tie, the element appearing first in the HTML document takes precedence.
The ALIGN attribute, deprecated in HTML 4.0, specifies the alignment of the
object. The values top, middle, and bottom specify the object's position with
respect to surrounding content on its left and right.
ALIGN=middle aligns the center of the object with the current baseline. To
center the object horizontally on the page, place the object in a centered
block, e.g.,
<P ALIGN=center><OBJECT DATA="foo.mov"
TYPE="video/quicktime"></OBJECT></P>
The other ALIGN values, left and right, specify a floating object; the
object is placed at the left or right margin and content flows around it. To
place content below the object, use <BR CLEAR=left|right|all> as appropriate.
The vertical-align and float properties of Cascading Style Sheets provide
more flexible methods of aligning objects.
The BORDER attribute, deprecated in HTML 4.0, specifies the width of the
object's border. Specifying BORDER=0 will eliminate the border around a
linked object in most browsers, though some allow the user to override this.
Authors should only use BORDER=0 if the object would be clearly recognizable
as a link, or as a method of de-emphasizing a link. For example:
<A HREF="reference/"><OBJECT DATA="icon/reference.gif"
WIDTH=90 HEIGHT=90 BORDER=0></OBJECT>Web Authoring
Reference</A>
The deprecated HSPACE and VSPACE attributes allow an author to suggest
horizontal gutters and vertical gutters, respectively, around the object. The
value must be in pixels and applies to both sides of the object. Style sheets
provide more flexibility in specifying the space around objects.
The OBJECT element is most useful as a BODY element and can be contained
within either inline or block-level elements. The contents of OBJECT should
be elements that can be contained within OBJECT's parent element. For example,
an A element containing an OBJECT should not have any block-level elements
as the contents of the OBJECT.
ΓòÉΓòÉΓòÉ 1.5.61. OL - Ordered list ΓòÉΓòÉΓòÉ
OL - Ordered List
Syntax
<OL>...</OL>
Attribute Specifications
o TYPE=[ 1 | a | A | i | I ] (numbering style)
o START= Number (starting number)
o COMPACT (compact display)
o common attributes
Contents
One or more LI elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The OL element defines an ordered list. The element contains one or more LI
elements that define the actual items of the list.
Unlike with an unordered list ( UL), the items of an ordered list have a
definite sequence. Items in an ordered list are numbered by the browser.
The deprecated TYPE attribute of OL suggests the numbering style on visual
browsers. The case-sensitive values are as follows:
o 1 (decimal numbers: 1, 2, 3, 4, 5, ...)
o a (lowercase alphabetic: a, b, c, d, e, ...)
o A (uppercase alphabetic: A, B, C, D, E, ...)
o i (lowercase Roman numerals: i, ii, iii, iv, v, ...)
o I (uppercase Roman numerals: I, II, III, IV, V, ...)
The numbering style on an individual list item can be suggested using the TYPE
attribute of LI. The list-style-type property of CSS provides greater
flexibility in suggesting numbering styles.
The deprecated START attribute suggests the starting number for the list and
defaults to 1. The value of START must be an integer, but the number may be
presented in a different form (for example, as a Roman numeral). While this
attribute is deprecated, there is currently no substitute for it in Cascading
Style Sheets.
The deprecated COMPACT attribute suggests that visual browsers render the
list compactly, perhaps with reduced spacing between items. This attribute is
not well supported among browsers.
ΓòÉΓòÉΓòÉ 1.5.62. OPTGROUP - Option group ΓòÉΓòÉΓòÉ
OPTGROUP - Option Group
Syntax
<OPTGROUP>...</OPTGROUP>
Attribute Specifications
o LABEL= Text (group label)
o DISABLED (disable group of choices)
o common attributes
Contents
One or more OPTION elements
Contained in
SELECT
The OPTGROUP element defines a group of choices within a SELECT menu.
OPTGROUP must contain one or more OPTION elements to define the actual
choices.
The required LABEL attribute specifies the group label presented to the user.
The LABEL should describe the group of choices available through the
OPTGROUP's OPTIONs. Each OPTION generally uses a LABEL attribute as well to
provide a shortened label that, together with the OPTGROUP's LABEL, gives a
complete description of the option. An example follows:
<P>Which Web browser do you use most often?
<SELECT NAME=browser>
<OPTGROUP LABEL="Netscape Navigator">
<OPTION LABEL="4.x or higher">
Netscape Navigator 4.x or higher
</OPTION>
<OPTION LABEL="3.x">Netscape Navigator 3.x</OPTION>
<OPTION LABEL="2.x">Netscape Navigator 2.x</OPTION>
<OPTION LABEL="1.x">Netscape Navigator 1.x</OPTION>
</OPTGROUP>
<OPTGROUP LABEL="Microsoft Internet Explorer">
<OPTION LABEL="4.x or higher">
Microsoft Internet Explorer 4.x or higher </OPTION>
<OPTION LABEL="3.x">Microsoft Internet Explorer 3.x</OPTION>
<OPTION LABEL="2.x">Microsoft Internet Explorer 2.x</OPTION>
<OPTION LABEL="1.x">Microsoft Internet Explorer 1.x</OPTION>
</OPTGROUP>
<OPTGROUP LABEL="Opera">
<OPTION LABEL="3.x or higher">
Opera 3.x or higher
</OPTION>
<OPTION LABEL="2.x">Opera 2.x</OPTION>
</OPTGROUP>
<OPTION>Other</OPTION>
</SELECT>
</P>
OPTGROUP is not well supported by current browsers, but its design allows
authors to use it today without sacrificing compatibility with non-supporting
browsers. Supporting browsers will render the preceding example using the
LABEL attribute of OPTION to provide just the version number, along with the
OPTGROUP's LABEL, which gives the full name of the application. This allows a
compact display with easy-to-use cascading menus.
Non-supporting browsers will ignore the OPTGROUP elements and LABEL
attributes, providing the full name and version for each choice. Thus authors
can fully use OPTGROUP despite its lack of browser support.
Note that, in HTML 4.0, OPTGROUP is limited to containing only OPTION
elements, thus preventing nested OPTGROUPs with multi-level cascades. Future
versions of HTML may add support for nested option groups.
The boolean DISABLED attribute makes the option group unavailable. The
options of a disabled option group cannot be selected by the user and are never
submitted with the form.
ΓòÉΓòÉΓòÉ 1.5.63. OPTION - Menu option ΓòÉΓòÉΓòÉ
OPTION - Menu Option
Syntax
<OPTION>...</OPTION>
Attribute Specifications
o VALUE= CDATA (value of option)
o SELECTED (choice initially selected)
o DISABLED (disable choice)
o LABEL= Text (option label)
o common attributes
Contents
Plain text (including entities)
Contained in
SELECT, OPTGROUP
The OPTION element defines a menu choice within a SELECT menu. The value of
the option, sent with a submitted form, is specified with the VALUE attribute.
In the absence of a VALUE attribute, the value is the content of the OPTION
element.
The boolean SELECTED attribute defines the OPTION to be initially selected.
A SELECT element can only have one OPTION selected at any time unless the
MULTIPLE attribute is present on SELECT.
If the SELECT element does not use the MULTIPLE or SIZE attributes, some
browsers will automatically (and incorrectly) select an option. To ensure that
a suitable option is selected, authors may wish to use the SELECTED attribute
on an OPTION. If no option is a suitable default, consider using a dummy
option, as in the following example:
<SELECT NAME="marital_status">
<OPTION SELECTED VALUE="">Select...</OPTION>
<OPTION>Single</OPTION>
<OPTION>Married</OPTION>
<OPTION>Separated</OPTION>
<OPTION>Divorced</OPTION>
<OPTION>Widowed</OPTION>
</SELECT>
The boolean DISABLED attribute, new in HTML 4.0 and poorly supported by
current browsers, makes the OPTION element unavailable. A disabled option
cannot be selected by the user and is never submitted with the form.
The LABEL attribute specifies the option label presented to the user. This
defaults to the content of the OPTION element, but the LABEL attribute allows
authors to more easily use OPTGROUP without sacrificing compatibility with
browsers that do not support option groups. The following example illustrates
the technique:
<P>Which Web browser do you use most often?
<SELECT NAME=browser>
<OPTGROUP LABEL="Netscape Navigator">
<OPTION LABEL="4.x or higher">
Netscape Navigator 4.x or higher
</OPTION>
<OPTION LABEL="3.x">Netscape Navigator 3.x</OPTION>
<OPTION LABEL="2.x">Netscape Navigator 2.x</OPTION>
<OPTION LABEL="1.x">Netscape Navigator 1.x</OPTION>
</OPTGROUP>
<OPTGROUP LABEL="Microsoft Internet Explorer">
<OPTION LABEL="4.x or higher">
Microsoft Internet Explorer 4.x or higher
</OPTION>
<OPTION LABEL="3.x">Microsoft Internet Explorer 3.x</OPTION>
<OPTION LABEL="2.x">Microsoft Internet Explorer 2.x</OPTION>
<OPTION LABEL="1.x">Microsoft Internet Explorer 1.x</OPTION>
</OPTGROUP>
<OPTGROUP LABEL="Opera">
<OPTION LABEL="3.x or higher">Opera 3.x or higher</OPTION>
<OPTION LABEL="2.x">Opera 2.x</OPTION>
</OPTGROUP>
<OPTION>Other</OPTION>
</SELECT>
</P>
OPTGROUP and OPTION's LABEL attribute were introduced together, so browsers
should support both features or neither of them. Supporting browsers will
render the preceding example using the LABEL attribute of OPTION to provide
just the version number, along with the OPTGROUP's LABEL, which gives the full
name of the application. This allows a compact display with cascading menus,
but many browsers do not yet support OPTGROUP. These browsers will ignore the
OPTGROUP elements and LABEL attributes, providing the full name and version
for each choice. Thus authors can fully use OPTGROUP despite its lack of
browser support.
ΓòÉΓòÉΓòÉ 1.5.64. P - Paragraph ΓòÉΓòÉΓòÉ
P - Paragraph
Syntax
<P>...</P>
Attribute Specifications
o ALIGN=[ left | center | right | justify ] (horizontal alignment)
o common attributes
Contents
Inline elements
Contained in
ADDRESS, APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DEL, DD, DIV,
FIELDSET, FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD,
TH
The P element defines a paragraph. The closing tag for P is optional, but
its use prevents common browser bugs with style sheets. Note that P cannot
contain block-level elements such as TABLE and ADDRESS.
The deprecated ALIGN attribute suggests the horizontal alignment for the
content of the paragraph on visual browsers. Possible values are left, right,
center, and justify. Style sheets provide greater flexibility in suggesting
paragraph alignment.
HTML does not specify a presentation for the P element. Visual browsers
commonly use block paragraphs with no first-line indent and separated by a
blank line, but some browsers allow the user to specify a different
presentation. An author can suggest paragraph indentation and spacing using
style sheets. The following CSS ruleset suggests a possible presentation for
paragraphs:
P { margin-top: 0; text-indent: 5% }
ΓòÉΓòÉΓòÉ 1.5.65. PARAM - Object parameter ΓòÉΓòÉΓòÉ
PARAM - Object Parameter
Syntax
<PARAM>
Attribute Specifications
o NAME= CDATA (property name)
o VALUE= CDATA (property value)
o VALUETYPE=[ data | ref | object ] (type of value)
o TYPE= ContentType (content-type of value resource)
o ID= ID
Contents
Empty
Contained in
APPLET, OBJECT
The PARAM element provides parameters for the OBJECT and APPLET elements.
An OBJECT or APPLET may contain any number of PARAM elements prior to the
alternate content that is also contained within the OBJECT or APPLET element.
The required NAME attribute of PARAM gives the name of the parameter while
the VALUE attribute gives the parameter's value. The parameters recognized
are specific to the kind of object being embedded or to the plug-in that
renders the embedded object. For example, a clock applet may accept parameters
to specify the style of the clock and the colors to use:
<OBJECT CLASSID="java:Clock.class"
CODETYPE="application/java" WIDTH=100 HEIGHT=100 TITLE="A
real live clock!" STANDBY="Do you know what time it is?">
<PARAM NAME=TYPE VALUE=ANALOG>
<PARAM NAME=BGCOLOR VALUE=WHITE>
<PARAM NAME=FGCOLOR VALUE=NAVY>
</OBJECT>
Note that the PARAM elements used in the preceding example would not change if
the APPLET element were used in place of OBJECT.
Objects such as videos, audio clips, and VRML worlds are typically handled by
browser plug-ins. Each plug-in recognizes certain parameters, which can make
choosing parameters difficult when the author does not know which plug-in the
user has. However, unsupported parameters should be safely ignored. The
following example uses parameters specific to the QuickTime movie plug-in as
well as parameters specific to the LiveAudio audio plug-in:
<OBJECT DATA="mlk.mov" TYPE="video/quicktime"
TITLE="Martin Luther King's "I Have a Dream"
speech" WIDTH=150 HEIGHT=150>
<PARAM NAME=pluginspage
VALUE="http://quicktime.apple.com/">
<PARAM NAME=autoplay VALUE=true>
<OBJECT DATA="mlk.wav" TYPE="audio/x-wav" TITLE="Martin
Luther King's "I Have a Dream" speech">
<PARAM NAME=autostart VALUE=true>
<PARAM NAME=hidden VALUE=true>
<A HREF="mlk.html">Full text of Martin Luther King's "I
Have a Dream" speech</A>
</OBJECT>
</OBJECT>
Note that only the parameters specified within the OBJECT and prior to the
alternate content are passed onto the plug-in, so that the pluginspage and
autoplay parameters are used if the QuickTime movie is played while the
autostart and hidden parameters are used if the audio clip is played.
The VALUETYPE parameter of PARAM designates the type of the VALUE attribute.
The default value for VALUETYPE is data, which indicates that the VALUE
attribute contains a string.
The ref value for VALUETYPE indicates that the VALUE attribute contains a
URI where run-time values are stored. The Internet media type of the resource
is specified by the TYPE attribute. The following example uses values with
VALUETYPE=ref to specify the location of images to animate and a sound to play
during the animation:
<OBJECT CLASSID="java:Animator.class"
CODETYPE="application/java" WIDTH=200 HEIGHT=300
TITLE="Wedding Photos">
<PARAM NAME=IMAGE1 VALUE="images/wedding/bride.jpg"
VALUETYPE=ref TYPE="image/jpeg">
<PARAM NAME=IMAGE2 VALUE="images/wedding/groom.jpg"
VALUETYPE=ref TYPE="image/jpeg">
<PARAM NAME=IMAGE3 VALUE="images/wedding/cake.jpg"
VALUETYPE=ref TYPE="image/jpeg">
<PARAM NAME=SOUND
VALUE="http://www.htmlhelp.com/sounds/weddingmarch.au"
VALUETYPE=ref TYPE="audio/basic">
</OBJECT>
The URI specified by VALUE is passed to the object without being resolved to
a full URL. In the preceding example, the Java class would be responsible for
resolving and fetching the contents of partial URIs like
"images/wedding/cake.jpg".
VALUETYPE also takes an object value, for use when a VALUE attribute
specifies an identifier of a separate OBJECT in the document. The following
example features a hypothetical application for interactively walking through
the frames of an animated GIF. The GIF is loaded in a separate OBJECT from
the application that uses it.
<OBJECT DECLARE ID=mygif DATA="animation.gif"
TYPE="image/gif">
</OBJECT>
<OBJECT CLASSID="framepicker">
<PARAM NAME=image VALUE="#mygif" VALUETYPE=object>
<IMG SRC="animation.gif" ALT="[Example of an animated
GIF]"> </OBJECT>
ΓòÉΓòÉΓòÉ 1.5.66. PRE - Preformatted text ΓòÉΓòÉΓòÉ
PRE - Preformatted Text
Syntax
<PRE>...</PRE>
Attribute Specifications
o WIDTH= Number (line width)
o common attributes
Contents
Inline elements except IMG, OBJECT, APPLET, BIG, SMALL, SUB, SUP,
FONT, BASEFONT
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The PRE element contains preformatted text. Visual browsers should render
preformatted text in a fixed-pitch font, should not collapse whitespace, and
should not wrap long lines.
PRE is useful for formatting computer code or poetry where whitespace is
important, but since preformatted text is inherently visual, authors should
avoid dependence on it wherever possible. When using PRE, authors should avoid
altering the element's fixed-pitch font or non-collapsing whitespace properties
by means of style sheets.
The following example features Java code in a PRE element:
<PRE><CODE CLASS=Java>
class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}
</CODE></PRE>
The code in the preceding example would be more difficult to read if it were
not preformatted, and so PRE is used to provide the proper spacing. Note that
the CODE element is also included to add structural information.
The deprecated WIDTH attribute of PRE tells the browser the expected line
length of the preformatted block so that a suitable font size or margin can be
used. Browsers ignore this attribute in practice.
The bidirectional algorithm that determines the directionality of text still
applies within the PRE element.
ΓòÉΓòÉΓòÉ 1.5.67. Q - Short quotation ΓòÉΓòÉΓòÉ
Q - Short Quotation
Syntax
<Q>...</Q>
Attribute Specifications
o CITE= URI (source of quotation)
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The Q element is used for short, inline quotations. For longer (block)
quotations, use the BLOCKQUOTE element.
The Q element's optional CITE attribute provides a URI of the source of the
quotation. Some examples follow:
<P>In the words of Albert Einstein,
<Q>God does <EM>not</EM> play dice.</Q></P>
<P>According to Dave Raggett,
<Q CITE="http://www.w3.org/Press/HTML4-REC">
HTML 4.0 gives Web designers the ability to create dynamic visually
exciting pages that are accessible to all.
</Q></P>
Note that authors should not include their own quotation marks when using the Q
element. However, this can be a problem since almost all current browsers lack
support for Q. Authors may prefer to avoid Q and insert their own quotation
marks. Another alternative is to use I in combination with Q so that the
quotation is distinguished from other text in most browsers. The previous
example could also be given as follows:
<P>According to Dave Raggett,
<I><Q CITE="http://www.w3.org/Press/HTML4-REC">
HTML 4.0 gives Web designers the ability to create dynamic visually
exciting pages that are accessible to all.
</Q></I></P>
Browsers supporting Q should properly handle nested quotations. They should
also use quotation marks suitable to the language of the quotation, based on
the LANG attribute of Q or the language of its parent.
ΓòÉΓòÉΓòÉ 1.5.68. S - Strike-through text ΓòÉΓòÉΓòÉ
S - Strike-through Text
Syntax
<S>...</S>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The S element, deprecated in HTML 4.0, suggests that text be rendered with a
strike-through style. In many cases, use of a phrase elemens such as DEL is
more appropriate since such elements express the meaning of the text more
clearly. However, since support for DEL among browsers is weak, S could be
useful in combination with DEL, as in the following example:
The latest version of HTML recommended by the W3C is HTML
<DEL DATETIME="1997-12-19T00:00:00-05:00"><S>3.2</S></DEL>
<INS DATETIME="1997-12-19T00:00:00-05:00">4.0</INS>.
Note that STRIKE is better supported than S (based on Netscape 2.x and 1.22
supporting STRIKE but not S), and so STRIKE should be used in place of S. There
does not appear to be any advantage to using both STRIKE and S; all browsers
that support S also seem to support STRIKE.
If DEL is not a suitable structure, style sheets should be used to complement
or replace instances of S. CSS1 provides the text-decoration property for
strike-through text.
ΓòÉΓòÉΓòÉ 1.5.69. SAMP - Sample output ΓòÉΓòÉΓòÉ
SAMP - Sample Output
Syntax
<SAMP>...</SAMP>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The SAMP element denotes sample output, such as from a program or script.
Visual browsers typically render SAMP as monospaced text, but authors can
suggest a rendering using style sheets. Since SAMP is a structural element,
it carries meaning, making it preferable to font style elements such as TT
when marking up sample output.
Example:
<P>When an undefined element is used in an HTML document, a validator
will give an error like the following:</P>
<P><SAMP>C:\SP\BIN\NSGMLSU.EXE:test.html:4:7:E:
element "FOOBAR" undefined</SAMP></P>
ΓòÉΓòÉΓòÉ 1.5.70. SCRIPT - Client-side script ΓòÉΓòÉΓòÉ
SCRIPT - Client-side Script
Syntax
<SCRIPT>...</SCRIPT>
Attribute Specifications
o TYPE= ContentType (content-type of scripting language)
o LANGUAGE= CDATA (scripting language name)
o SRC= URI (external script location)
o CHARSET= Charset (character encoding of external script)
o DEFER (script execution may wait)
Contents
An embedded script
Contained in
HEAD, inline elements, block-level elements
The SCRIPT element includes a client-side script in the document.
Client-side scripts allow greater interactivity in a document by responding to
user events. For example, a script could be used to check the user's form
input prior to submission to provide immediate notice of any errors by the
user.
Note that not all browsers support client-side scripting, and supporting
browsers allow the user to disable scripting, so authors should avoid
dependence on client-side scripting wherever possible. The NOSCRIPT element
can be used to provide content for browsers that do not support client-side
scripting or have it disabled. In the case of form validation, any error
checking done by the client-side script should be repeated by the CGI script
or Java servlet that handles the submission at the server.
Also note that different browsers support different variants of scripting
languages with different bugs. Authors are encouraged to check their scripts
on as many browsers as possible. Browsers that support client-side scripting
include Netscape Navigator 2.0 and up, Microsoft Internet Explorer 3.0 and
up, and Opera 3.0 and up.
The required TYPE attribute of SCRIPT specifies the media type of the
scripting language, e.g., text/javascript. However, most browsers only support
the deprecated LANGUAGE attribute, which specifies the language name.
Examples of supported LANGUAGE values include JavaScript, JavaScript1.1, and
VBScript. The values are not case sensitive.
Browsers will ignore scripts with LANGUAGE values that they do not support.
For example, Netscape Navigator 3.0 will execute scripts with
LANGUAGE="JavaScript" or LANGUAGE="JavaScript1.1" but will ignore scripts
with LANGUAGE="JavaScript1.2" or LANGUAGE="VBScript".
In the absence of the LANGUAGE attribute, browsers typically assume that the
language is JavaScript 1.0. As there is no established convention for
indicating the version of JavaScript via the TYPE attribute, we recommend that
authors continue to use LANGUAGE to specify the language and version where it
differs from JavaScript 1.0.
An embedded script is given as the content of the SCRIPT element. The SRC
attribute allows authors to reuse code by specifying an external script. The
optional CHARSET attribute gives the character encoding of the external script
(typically ISO-8859-1). If the browser is unable to fetch the external script
it will execute any embedded script; otherwise it will ignore the embedded
script. An example follows:
<SCRIPT TYPE="text/javascript" SRC="foo.js" CHARSET="ISO-8859-1">
<!--
// embedded script, only executed if foo.js is unavailable
// -->
</SCRIPT>
Netscape Navigator requires that external scripts be served with a Content-Type
of application/x-javascript.
The DEFER attribute indicates that the browser may wait to parse the script
until the rest of the document has been rendered. Scripts that use DEFER must
not generate any document content, and should not be required to respond to
user events (e.g., form submission) that may occur while the document is
loading. The DEFER attribute can be useful for delaying scripts that pre-load
images or harass the user with scrolling messages in the status bar, though
current browsers do not generally support this attribute.
The SCRIPT element may occur any number of times in the document HEAD or
BODY. Typically the SCRIPT element is used in the HEAD unless it generates
BODY content.
Pre- HTML 3.2 browsers, unaware of the SCRIPT element, will treat the content
of SCRIPT as normal HTML. To make these browsers ignore the SCRIPT's content,
scripting languages generally allow SGML comments to be used around an
embedded script. For example:
<SCRIPT TYPE="text/javascript">
<!-- comment to end of line
document.write("foo");
// comment to end of line -->
</SCRIPT>
Note that "-->" is contained within a JavaScript single-line comment (started
with two slashes).
Technically, the first occurrence of "</" followed by any letter is considered
the end tag for the SCRIPT element. While browsers are forgiving in this,
authors should avoid using strings such as "</P>" in their embedded scripts.
JavaScript allows authors to use a backslash to avoid ending the SCRIPT
element prematurely, e.g., document.write("<\/P>").
ΓòÉΓòÉΓòÉ 1.5.71. SELECT - Option selector ΓòÉΓòÉΓòÉ
SELECT - Option Selector
Syntax
<SELECT>...</SELECT>
Attribute Specifications
o NAME= CDATA (key in submitted form)
o MULTIPLE (allow multiple selections)
o SIZE= Number (number of visible options)
o DISABLED (disable element)
o TABINDEX= Number (position in tabbing order)
o ONFOCUS= Script (element received focus)
o ONBLUR= Script (element lost focus)
o ONCHANGE= Script (element value changed)
o common attributes
Contents
One or more OPTGROUP or OPTION elements
Contained in
Block-level elements, inline elements except BUTTON
The SELECT element defines a form control for the selection of options. While
SELECT is most useful within a FORM, HTML 4.0 allows SELECT in any
block-level or inline element other than BUTTON. However, Netscape
Navigator will not display any SELECT elements outside of a FORM.
The SELECT element contains one or more OPTGROUP or OPTION elements to
provide a menu of choices for the user. Each choice is contained within an
OPTION element. Choices can be grouped logically through the OPTGROUP element.
SELECT's NAME attribute provides the key sent to the server with the value of
the selected option.
By default, the user can only select one option. The boolean MULTIPLE
attribute allows the user to select multiple options, which are submitted as
separate name/value pairs. The following example uses the MULTIPLE attribute
to allow the selection of one or more options:
<P>Select one or more sections to search:
<SELECT NAME=sections MULTIPLE>
<OPTION>Web Authoring Reference</OPTION>
<OPTION>FAQ Archives</OPTION>
<OPTION>Design Elements</OPTION>
<OPTION>Tools</OPTION>
<OPTION>Feature Article</OPTION>
</SELECT>
</P>
The boolean DISABLED attribute, new in HTML 4.0 and poorly supported by
current browsers, makes the SELECT element unavailable. The user is unable to
edit the disabled selection, no value is submitted with the form, the SELECT
element cannot receive focus, and the element is skipped when navigating the
document by tabbing.
The TABINDEX attribute specifies a number between 0 and 32767 to indicate the
tabbing order of the element. A SELECT element with TABINDEX=0 or no
TABINDEX attribute will be visited after any elements with a positive
TABINDEX. Among positive TABINDEX values, the lower number receives focus
first. In the case of a tie, the element appearing first in the HTML document
takes precedence.
The SIZE attribute of SELECT hints that visual browsers should display the
element as a list box with the specified number of options visible at any time.
A scroll bar would allow access to any non-visible options. The SIZE
attribute is especially useful in SELECT elements with numerous OPTIONs and
multiple selections allowed. In such a situation, some visual browsers will
render the entire list in one large box without scrolling; a suitable SIZE
attribute helps such browsers give a more appropriate presentation.
The SELECT element also takes a number of attributes to specify client-side
scripting actions for various events. In addition to the core events common
to most elements, SELECT accepts the following event attributes:
o ONFOCUS, when the element receives focus;
o ONBLUR, when the element loses focus;
o ONCHANGE, when the element loses focus and its value has changed since it
received focus.
ΓòÉΓòÉΓòÉ 1.5.72. SMALL - Small text ΓòÉΓòÉΓòÉ
SMALL - Small Font
Syntax
<SMALL>...</SMALL>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements except PRE
The SMALL element suggests that text be rendered in a smaller font. Since HTML
4.0 has no element to indicate de-emphasis, SMALL is often useful for this
purpose. For example:
<P><SMALL>Copyright ╨╣ 1998 Liam Quinn.
All rights reserved.</SMALL></P>
Most browsers support nested SMALL elements, but this practice should be
avoided. Since different users have different font sizes and eyesight,
significant changes in font size can leave text too small to read even though
it may look fine to the author.
Using style sheets in place of SMALL provides greater flexibility in changing
the presentation. The previous example could also be marked up as follows:
<P CLASS=copyright>Copyright ╨╣ 1998 Liam Quinn.
All rights reserved.</P>
This could then be linked to the following style sheet:
.copyright {
font-size: smaller;
text-align: center
}
@media aural {
.copyright { volume: soft }
}
ΓòÉΓòÉΓòÉ 1.5.73. SPAN - Generic inline container ΓòÉΓòÉΓòÉ
SPAN - Generic Inline Container
Syntax
<SPAN>...</SPAN>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The SPAN element is a generic inline container. SPAN carries no structural
meaning itself, but it can be used to provide extra structure through its
LANG, DIR, CLASS, and ID attributes. Style sheets are often used to
suggest a presentation for a given class or ID.
SPAN should only be used where no other HTML inline element provides a
suitable meaning. If a presentation such as bold or italic text would be
suitable on visual browsers, authors may prefer to use an appropriate font
style element. For example:
<P><SPAN LANG=fr>La Rщvolution Tranquille</SPAN>
shook Quebec in the early 1960's.
<P><I LANG=fr>La Rщvolution Tranquille</I>
shook Quebec in the early 1960's.
These examples are identical in meaning, but the second example uses the I
element to suggest italic text.
DIV is a block-level equivalent of SPAN for containing block-level elements
such as P and TABLE.
ΓòÉΓòÉΓòÉ 1.5.74. STRIKE - Strike-through text ΓòÉΓòÉΓòÉ
STRIKE - Strike-through Text
Syntax
<STRIKE>...</STRIKE>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The STRIKE element, deprecated in HTML 4.0, suggests that text be rendered with
a strike-through style. In many cases, use of a phrase elemens such as DEL is
more appropriate since such elements express the meaning of the text more
clearly. However, since support for DEL among browsers is weak, STRIKE is
useful in combination with DEL, as in the following example:
The latest version of HTML recommended by the W3C is HTML
<DEL DATETIME="1997-12-19T00:00:00-05:00"><STRIKE>3.2</STRIKE></DEL>
<INS DATETIME="1997-12-19T00:00:00-05:00">4.0</INS>.
If DEL is not a suitable structure, style sheets should be used to complement
or replace instances of STRIKE. CSS1 provides the text-decoration property for
strike-through text.
ΓòÉΓòÉΓòÉ 1.5.75. STRONG - Strong emphasis ΓòÉΓòÉΓòÉ
STRONG - Strong Emphasis
Syntax
<STRONG>...</STRONG>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The STRONG element gives strong emphasis to its contents. Visual browsers
typically render STRONG as bold text, but authors can suggest a rendering
using style sheets. Since STRONG is a structural element, it carries meaning,
making it preferable to font style elements such as B when strong emphasis is
the intended meaning.
For weaker emphasis, use the EM element.
ΓòÉΓòÉΓòÉ 1.5.76. STYLE - Embedded style sheet ΓòÉΓòÉΓòÉ
STYLE - Embedded Style Sheet
Syntax
<STYLE>...</STYLE>
Attribute Specifications
o TYPE= ContentType (content-type of style language)
o MEDIA= MediaDesc (media to apply style to)
o TITLE= Text (title of style sheet)
o internationalization attributes (for the TITLE)
Contents
An embedded style sheet
Contained in
HEAD
The STYLE element embeds a style sheet in the document. Any number of STYLE
elements may be contained in the HEAD of a document.
The required TYPE attribute of STYLE is used to specify the Internet media
type of the style language. For Cascading Style Sheets, the TYPE attribute
value should be text/css.
The optional TITLE attribute gives a title for the style sheet. Without a
TITLE attribute, the style sheet is always applied when style sheets are
enabled. With a TITLE attribute, the style sheet is automatically applied but
the user may choose to disable the style sheet while keeping or enabling other
style sheets. Style sheets with the same title are considered to be the same
style sheet.
Most current browsers ignore the TITLE attribute on style sheets and do not
allow the user to selectively enable or disable individual style sheets.
The MEDIA attribute specifies the media on which the style sheet should be
applied. This allows authors to restrict a style sheet to certain output
devices, such as printers or aural browsers. The attribute's value is a
comma-separated list of media descriptors. The following media descriptors are
defined in HTML 4.0 and are case-sensitive:
o screen (the default), for non-paged computer screens;
o tty, for fixed-pitch character grid displays (such as the display used by
Lynx);
o tv, for television-type devices with low resolution and limited
scrollability;
o projection, for projectors;
o handheld, for handheld devices (characterized by a small, monochrome display
and limited bandwidth);
o print, for output to a printer;
o braille, for braille tactile feedback devices;
o aural, for speech synthesizers;
o all, for all devices.
Netscape Navigator 4.x incorrectly ignores any STYLE element with a MEDIA
value other than screen. For example, MEDIA="screen, projection" will cause
the style sheet to be ignored by Navigator 4.x, even if the presentation device
is a computer screen. Navigator 4.x also ignores style sheets declared with
MEDIA=all. Most other browsers ignore the MEDIA attribute.
An example of an embedded style sheet follows:
<STYLE TYPE="text/css" MEDIA=screen>
<!--
BODY { background: url(foo.gif) red; color: black }
P EM { background: yellow; color: black }
.note { margin-left: 5em; margin-right: 5em }
-->
</STYLE>
Pre- HTML 3.2 browsers, unaware of the STYLE element, would normally show its
contents as if they were part of the BODY, thus making the style sheet visible
to the user. To prevent this, style languages like CSS allow the style sheet
to be contained within an SGML comment (<!-- comment -->), as in the preceding
example.
An embedded style sheet should be used when a single document has a unique
style. If the same style sheet is used in multiple documents, then an external
style sheet would be more appropriate.
ΓòÉΓòÉΓòÉ 1.5.77. SUB - Subscript ΓòÉΓòÉΓòÉ
SUB - Subscript
Syntax
<SUB>...</SUB>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The SUB element is used for subscripts. Since SUB is inherently
presentational, it should not be relied upon to express a given meaning.
However, it can be useful for chemical formulas and mathematical indices, where
the subscript presentation is helpful but not required. For example:
Chemical formulas include H<SUB>2</SUB>O (water) and
C<SUB>21</SUB>H<SUB>27</sub>NO (methadone).
Let <VAR>x</VAR> = <VAR>x<SUB>1</SUB></VAR> +
<VAR>x<SUB>2</SUB></VAR> + ... +
<VAR>x<SUB>n</SUB></VAR>.
ΓòÉΓòÉΓòÉ 1.5.78. SUP - Superscript ΓòÉΓòÉΓòÉ
SUP - Superscript
Syntax
<SUP>...</SUP>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The SUP element is used for superscripts. Since SUP is inherently
presentational, it should not be relied upon to express a given meaning.
However, it can be useful for mathematical exponents where the context implies
the meaning of the exponent, as well as other cases where superscript
presentation is helpful but not required. For example:
The rent is due on the 1<SUP>st</SUP> of each month.
An example of a quadratic polynomial is <STRONG>3<VAR>x</VAR>
<SUP CLASS=exponent>2</SUP> + 5<VAR>x</VAR> - 7</STRONG>.
The following two examples are ambiguous when presented on a browser incapable
of superscript text:
2<SUP CLASS=exponent>4</SUP> = 16
sin<SUP CLASS=exponent>2</SUP><VAR>x</VAR> + cos
<SUP CLASS=exponent>2</SUP><VAR>x</VAR> = 1
There is no simple solution for this problem. One could use notation such as
2^4 to represent "two raised to the exponent four." If it gains browser
support, MathML should provide a more suitable solution in the future.
ΓòÉΓòÉΓòÉ 1.5.79. TABLE - Table ΓòÉΓòÉΓòÉ
TABLE - Table
Syntax
<TABLE>...</TABLE>
Attribute Specifications
o SUMMARY= Text (purpose/structure of table)
o WIDTH= Length (table width)
o BORDER= Pixels (border width)
o FRAME=[ void | above | below | hsides | lhs | rhs | vsides | box | border
] (outer border)
o RULES=[ none | groups | rows | cols | all ] (inner borders)
o CELLSPACING= Length (spacing between cells)
o CELLPADDING= Length (spacing within cells)
o ALIGN=[ left | center | right ] (table alignment)
o BGCOLOR= Color (table background color)
o common attributes
Contents
An optional CAPTION, followed by zero or more COL and COLGROUP
elements, followed by an optional THEAD element, an optional TFOOT
element, and then one or more TBODY elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The TABLE element defines a table for multi-dimensional data arranged in rows
and columns. TABLE is commonly used as a layout device, but authors should
avoid this practice as much as possible. Tables can cause problems for users
of narrow windows, large fonts, or non-visual browsers, and these problems are
often accentuated when tables are used solely for layout purposes. As well,
current visual browsers will not display anything until the complete table has
been downloaded, which can have very noticeable effects when an entire document
is laid out within a TABLE. Authors should try to use style sheets in place
of TABLE for layout, though bugs in current browser implementations of style
sheets can make this difficult.
The TABLE may contain a number of optional elements to provide a rich
structure to the table. The optional CAPTION element gives a caption for the
table and is followed by optional COL and COLGROUP elements that specify
column widths and groupings. The THEAD, TFOOT, and TBODY elements then
follow with groups of rows. The optional THEAD and TFOOT elements contain
header and footer rows, respectively, while TBODY elements supply the table's
main row groups. A row group contains TR elements for individual rows, and
each TR contains TH or TD elements for header cells or data cells,
respectively.
At least one TBODY element is required within a TABLE, but TBODY's start and
end tags are both optional if there is only one TBODY and no THEAD or TFOOT.
A simple table could thus be expressed as follows:
<TABLE>
<TR>
<TH>Abbreviation</TH>
<TH>Long Form</TH>
</TR>
<TR>
<TD>AFAIK</TD>
<TD>As Far As I Know</TD>
</TR>
<TR>
<TD>IMHO</TD>
<TD>In My Humble Opinion</TD>
</TR>
<TR>
<TD>OTOH</TD>
<TD>On The Other Hand</TD>
</TR>
</TABLE>
The same table could be expressed with a richer structure by grouping rows and
adding a caption, as in the next example. The extra structural information
allows an author to more easily suggest the presentation of the table using
style sheets or TABLE's presentational attributes.
<TABLE>
<CAPTION>Common Usenet Abbreviations</CAPTION>
<THEAD>
<TR>
<TH>Abbreviation</TH>
<TH>Long Form</TH>
</TR>
</THEAD>
<TBODY>
<TR>
<TD>AFAIK</TD>
<TD>As Far As I Know</TD>
</TR>
<TR>
<TD>IMHO</TD>
<TD>In My Humble Opinion</TD>
</TR>
<TR>
<TD>OTOH</TD>
<TD>On The Other Hand</TD>
</TR>
</TBODY>
</TABLE>
The TABLE element takes an optional SUMMARY attribute to describe the purpose
and/or structure of the table. The overview provided by the SUMMARY attribute
is particularly helpful to users of non-visual browsers. With simple tables, a
good CAPTION is usually a sufficient summary, but complex tables may benefit
from a more detailed overview via the SUMMARY attribute. The following
example uses SUMMARY to describe a table. Note that the summary could also be
included in a paragraph before the table, which is helpful since few browsers
support SUMMARY.
<TABLE SUMMARY="This table gives the character entity reference,
decimal character reference, and hexadecimal character
reference for symbols and Greek letters.">
<COLGROUP>
<COLGROUP SPAN=3>
<THEAD>
<TR>
<TH SCOPE=col>Character</TH>
<TH SCOPE=col>Entity</TH>
<TH SCOPE=col>Decimal</TH>
<TH SCOPE=col>Hex</TH>
</TR>
</THEAD>
<TBODY>
<TR>
<TD SCOPE=row>Latin small f with hook</TD>
<TD>ƒ</TD>
<TD>ƒ</TD>
<TD>ƒ</TD>
</TR>
...
</TBODY>
</TABLE>
The TABLE element also takes a number of optional attributes to provide
presentational hints in visual browsers. Equivalents of these attributes in
Cascading Style Sheets are under development and not widely supported by
browsers.
o
The WIDTH attribute specifies the width of the table as a number of pixels
or as a percentage of the available horizontal space. Widths in pixels should
be avoided, especially widths above 500 pixels, since this causes unnecessary
horizontal scrolling for some users.
o
The BORDER attribute specifies the width in pixels of the border around a
table.
o
The FRAME attribute, poorly supported by browsers, specifies which sides of
the table's outer border are visible. Possible values are void for no
border, above for a top border only, below for a bottom border only, hsides
for left and right borders only, vsides for top and bottom borders only, lhs
for a left border only, rhs for a right border only, and either box or
border for a border on all sides. The default value is void unless the
BORDER attribute gives a positive width, in which case FRAME=border is the
default. <TABLE BORDER> is a valid, well-supported shorthand for <TABLE
FRAME=border>.
o
The RULES attribute, poorly supported by browsers, specifies the borders
between table cells. Possible values are none for no inner borders, groups
for borders between row groups and column groups only, rows for borders
between rows only, cols for borders between columns only, and all for
borders between all cells. None is the default value if BORDER=0 is used
or if no BORDER attribute is given. All is the default value for any other
use of BORDER.
o
The CELLSPACING attribute defines the amount of space between table cells,
and the CELLPADDING attribute defines the amount of space within table cells
(i.e., between the border and cell contents). The value may be given as a
number of pixels or as a percentage, though most browsers do not support
percentages, treating CELLPADDING="20%" as if it were CELLPADDING="20". A
percentage value is relative to the vertical space available for vertical
padding or spacing, and the amount is split evenly between the top and
bottom. Horizontal padding and spacing behave similarly. The padding or
spacing is always applied to all four sides.
The padding properties of Cascading Style Sheets allow an author to
suggest different padding for different sides, but are not as well supported
as the CELLPADDING attribute.
o
The deprecated ALIGN attribute suggests the horizontal alignment of the
table on visual browsers. Possible values are left, right, and center.
Browsers generally present left- or right-aligned tables as floating tables,
with the content following the TABLE flowing around it. To prevent content
from flowing around the table, use <BR CLEAR=all> after the end of the TABLE.
Since many browsers do not support ALIGN=center with TABLE, authors may wish
to place the TABLE within a CENTER element.
Style sheets provide more flexibility in suggesting table alignment but with
less browser support than the ALIGN attribute.
o
The deprecated BGCOLOR attribute suggests a background color for the table.
The combination of this attribute with < FONT COLOR=...> can leave invisible
or unreadable text on Netscape Navigator 2.x, which does not support BGCOLOR
on table elements. BGCOLOR is dangerous even on supporting browsers, since
most fail to override it when overriding other author-specified colors. Style
sheets provide a safer, more flexible method of specifying a table's
background color.
ΓòÉΓòÉΓòÉ 1.5.80. TBODY - Table body ΓòÉΓòÉΓòÉ
TBODY - Table Body
Syntax
<TBODY>...</TBODY>
Attribute Specifications
o ALIGN=[ left | center | right | justify | char ] (horizontal alignment of
cells in group)
o CHAR= Character (alignment character for cells)
o CHAROFF= Length (alignment character offset)
o VALIGN=[ top | middle | bottom | baseline ] (vertical alignment of cells
in group)
o common attributes
Contents
One or more TR elements
Contained in
TABLE
The TBODY element defines a group of data rows in a table. A TABLE must
have one or more TBODY elements, which must follow the optional TFOOT. The
TBODY end tag is always optional. The start tag is optional when the table
contains only one TBODY and no THEAD or TFOOT. This allows the simple
table structure of HTML 3.2 to still be valid:
<TABLE>
<TR>
<TH>Abbreviation</TH>
<TH>Long Form</TH>
</TR>
<TR>
<TD>AFAIK</TD>
<TD>As Far As I Know</TD>
</TR>
</TABLE>
By explicitly grouping rows with THEAD, TFOOT, and TBODY, authors give browsers
the ability to present a long table with a scrolling body and static header and
footer rows. Using TBODY also provides the ability to easily suggest different
presentations for different row groups through style sheets. While few
browsers currently support TBODY, it can be used with no harm on non-supporting
browsers.
The following example gives a table of SI units of measure. TBODY elements
are used to group rows based on whether the unit is classed as a "base" unit,
"derived" unit, or "supplementary" unit.
<TABLE SUMMARY="This table lists SI (International System) units of
measure, giving the name of the unit, its symbol, and
the quantity that it measures.">
<CAPTION>SI Units</CAPTION>
<THEAD>
<TR>
<TH SCOPE=col>Name</TH>
<TH SCOPE=col>Symbol</TH>
<TH SCOPE=col>Quantity</TH>
</TR>
</THEAD>
<TBODY CLASS=base>
<TR>
<TD SCOPE=row>meter</TD>
<TD>m</TD>
<TD>length</TD> </TR>
<TR>
<TD SCOPE=row>kilogram</TD>
<TD>kg</TD>
<TD>mass</TD>
</TR>
...
</TBODY>
<TBODY CLASS=derived>
<TR>
<TD SCOPE=row>hertz</TD>
<TD>Hz</TD>
<TD>frequency</TD>
</TR>
<TR>
<TD SCOPE=row>pascal</TD>
<TD>Pa</TD>
<TD>pressure</TD>
</TR>
...
</TBODY>
<TBODY CLASS=supplementary>
<TR>
<TD SCOPE=row>radian</TD>
<TD>rad</TD>
<TD>plane angle</TD>
</TR>
...
</TBODY>
</TABLE>
In addition to the attributes common to most elements, TBODY takes
presentational attributes for specifying the alignment of cell data. Since few
browsers support TBODY, authors may wish to specify these attributes on the TR
or TD elements instead.
The ALIGN attribute specifies the horizontal alignment for each cell in the
row group. Possible values are left, center, right, justify, and char.
ALIGN=char aligns a cell's contents on the character given in the CHAR
attribute. The default value for the CHAR attribute is the decimal point of
the current language--a period in English. The CHAROFF attribute specifies
the offset to the first occurrence of the alignment character. The attribute's
value is a number in pixels or a percentage of the cell's width; CHAROFF="50%"
centers the alignment character horizontally in a cell.
The VALIGN attribute specifies the vertical position of a cell's contents.
Possible values are:
o top, which positions data at the top of the cell;
o middle, the default value, which centers the cell data vertically;
o bottom, which positions data at the bottom of the cell;
o baseline, which specifies that the first line of each cell in the row with
ALIGN=baseline should occur on a common baseline.
ΓòÉΓòÉΓòÉ 1.5.81. TD - Table data cell ΓòÉΓòÉΓòÉ
TD - Table Data Cell
Syntax
<TD>...</TD>
Attribute Specifications
o ROWSPAN= Number (rows spanned by the cell)
o COLSPAN= Number (columns spanned by the cell)
o HEADERS= IDREFS (list of header cells for current cell)
o ABBR= Text (abbreviation for header cell)
o SCOPE=[ row | col | rowgroup | colgroup ] (cells covered by header cell)
o AXIS= CDATA (category of header cell)
o ALIGN=[ left | center | right | justify | char ] (horizontal alignment)
o CHAR= Character (alignment character)
o CHAROFF= Length (alignment character offset)
o VALIGN=[ top | middle | bottom | baseline ] (vertical alignment)
o WIDTH= Pixels (cell width)
o HEIGHT= Pixels (cell height)
o NOWRAP (suppress word wrap)
o BGCOLOR= Color (cell background color)
o common attributes
Contents
Inline elements, block-level elements
Contained in
TR
The TD element defines a data cell in a table. TD elements are contained
within a TR element (a table row), which may also contain TH elements for
header cells. When a cell's contents act as both header information and table
data, TD should be used.
The ROWSPAN and COLSPAN attributes of TD specify the number of rows and the
number of columns, respectively, that are spanned by the cell. The default
value is 1. The special value 0 indicates that the cell spans all rows or
columns to the end of the table. The value 0 is ignored by most browsers, so
authors may wish to calculate the exact number of rows or columns spanned and
use that value.
The HEADERS attribute specifies the header cells that apply to the TD. The
value is a space-separated list of the header cells' ID attribute values. The
HEADERS attribute allows non-visual browsers to render the header information
for a given cell.
The ABBR, SCOPE, and AXIS attributes should only be used if the cell provides
header information. Like HEADERS, these attributes are new in HTML 4.0 and not
well supported, though they should be particularly helpful to non-visual
browsers in the future.
ABBR gives an abbreviated version of the cell's content. This allows visual
browsers to use the short form if space is limited, and non-visual browsers can
give a cell's header information in an abbreviated form before rendering each
cell.
The SCOPE attribute specifies the cells for which the TD element provides
header information. SCOPE is a simpler alternative to using HEADERS if the
arrangement of header cells is not complex. Possible values are as follows:
o row, when the TD provides header information for the rest of the row;
o col, when the TD provides header information for the rest of the column;
o rowgroup, when the TD gives header information for the rest of the row group
(i.e., the remaining cells of the THEAD, TFOOT, or TBODY);
o colgroup, when the TD gives header information for the rest of the column
group (i.e., the remaining cells of the COLGROUP).
The AXIS attribute provides a method of categorizing cells. The attribute's
value is a comma-separated list of category names. See the HTML 4.0
Recommendation's section on categorizing cells for an application of AXIS.
In addition to the attributes common to most elements, TD takes a number of
presentational attributes. Style sheets provide a more flexible way to suggest
a presentation for table cells, but TD's presentational attributes are more
widely supported by current browsers.
The ALIGN attribute specifies the horizontal alignment for the cell. Possible
values are left, center, right, justify, and char. ALIGN=char, poorly supported
among browsers, aligns a cell's contents on the character given in the CHAR
attribute. The default value for the CHAR attribute is the decimal point of
the current language--a period in English. The CHAROFF attribute specifies
the offset to the first occurrence of the alignment character. The attribute's
value is a number in pixels or a percentage of the cell's width; CHAROFF="50%"
centers the alignment character horizontally in a cell.
The VALIGN attribute specifies the vertical position of a cell's contents.
Possible values are:
o top, which positions data at the top of the cell;
o middle, the default value, which centers the cell data vertically;
o bottom, which positions data at the bottom of the cell;
o baseline, which specifies that the first line of each cell in the row with
ALIGN=baseline should occur on a common baseline.
The WIDTH, HEIGHT, NOWRAP, and BGCOLOR attributes are all deprecated in favor
of style sheets. WIDTH and HEIGHT suggest the cell's width and height in
pixels. The boolean NOWRAP attribute tells visual browsers to disable word
wrap for the cell, which can result in unnecessary horizontal scrolling
depending on the user's window width and font size.
The BGCOLOR attribute suggests a background color for the cell. The
combination of this attribute with < FONT COLOR=...> can leave invisible or
unreadable text on Netscape Navigator 2.x, which does not support BGCOLOR on
table elements. BGCOLOR is dangerous even on supporting browsers, since most
fail to override it when overriding other author-specified colors. Style sheets
provide a safer, more flexible method of specifying a table's background color.
ΓòÉΓòÉΓòÉ 1.5.82. TEXTAREA - Multi-line text input ΓòÉΓòÉΓòÉ
TEXTAREA - Multi-line Text Input
Syntax
<TEXTAREA>...</TEXTAREA>
Attribute Specifications
o NAME= CDATA (key in submitted form)
o ROWS= Number (number of rows)
o COLS= Number (number of columns)
o DISABLED (disable element)
o READONLY (prevent changes)
o ACCESSKEY= Character (shortcut key)
o TABINDEX= Number (position in tabbing order)
o ONFOCUS= Script (element received focus)
o ONBLUR= Script (element lost focus)
o ONSELECT= Script (element text selected)
o ONCHANGE= Script (element value changed)
o common attributes
Contents
Plain text (including entities)
Contained in
Block-level elements, inline elements except BUTTON
The TEXTAREA element defines a form control for the user to enter multi-line
text input. While TEXTAREA is most useful within a FORM, HTML 4.0 allows
TEXTAREA in any block-level or inline element other than BUTTON. However,
Netscape Navigator will not display any TEXTAREA elements outside of a FORM.
The initial value of the TEXTAREA is provided as the content of the element
and must not contain any HTML tags. When a form is submitted, the current
value of any TEXTAREA element within the FORM is sent to the server as a
name/value pair. The TEXTAREA element's NAME attribute provides the name
used.
The required ROWS and COLS attributes specify the number of visible rows and
columns, respectively, in a visual browser. These attributes provide a guide
for the user rather than a restriction; browsers allow an unlimited amount of
text input in theory, though in practice many browsers limit the contents of a
TEXTAREA to 32 or 64 kilobytes. Author restrictions on the amount of data
entered should be enforced by the CGI script or Java servlet handling the
form.
The boolean READONLY attribute, new in HTML 4.0 and poorly supported by
current browsers, prevents the user from editing the content of the TEXTAREA.
Read-only elements are still submitted with the form. The DISABLED attribute,
also poorly supported, disables the TEXTAREA. Disabled elements are read-only
elements with the added restrictions that the values are not submitted with the
form, the elements cannot receive focus, and the elements are skipped when
navigating the document by tabbing.
The ACCESSKEY attribute specifies a single Unicode character as a shortcut key
for giving focus to the TEXTAREA. Authors can set the access key on the
TEXTAREA element or the LABEL element associated with it. Entities (e.g.
é) may be used as the ACCESSKEY value.
The TABINDEX attribute specifies a number between 0 and 32767 to indicate the
tabbing order of the element. A TEXTAREA with TABINDEX=0 or no TABINDEX
attribute will be visited after any elements with a positive TABINDEX. Among
positive TABINDEX values, the lower number receives focus first. In the case
of a tie, the element appearing first in the HTML document takes precedence.
The TEXTAREA element also takes a number of attributes to specify client-side
scripting actions for various events. In addition to the core events common
to most elements, TEXTAREA accepts the following event attributes:
o ONFOCUS, when the element receives focus;
o ONBLUR, when the element loses focus;
o ONSELECT, when text in the element is selected;
o ONCHANGE, when the element loses focus and its value has changed since it
received focus.
ΓòÉΓòÉΓòÉ 1.5.83. TFOOT - Table foot ΓòÉΓòÉΓòÉ
TFOOT - Table Foot
Syntax
<TFOOT>...</TFOOT>
Attribute Specifications
o ALIGN=[ left | center | right | justify | char ] (horizontal alignment of
cells in group)
o CHAR= Character (alignment character for cells)
o CHAROFF= Length (alignment character offset)
o VALIGN=[ top | middle | bottom | baseline ] (vertical alignment of cells
in group)
o common attributes
Contents
One or more TR elements
Contained in
TABLE
The TFOOT element defines a group of footer rows in a table. A TABLE may
have one TFOOT, which must follow the optional THEAD and precede the required
TBODY.
By explicitly grouping footer rows with TFOOT, authors give browsers the
ability to include the footer rows on each page of a printed, multi-page table,
as well as the ability to present a long table with a scrolling body and static
footer rows. However, few browsers currently support TFOOT, and the
requirement that it be placed before the TBODY may make it unsuitable for
non-supporting browsers. If the presentation of footer rows prior to body rows
is not acceptable, authors should avoid using TFOOT until browser support is
greater.
A table footer may provide a summary row or footnotes that apply to the entire
table or portions of it. The following example uses TFOOT to contain footnotes
for a table:
<TABLE SUMMARY="This table lists program available at the university
based on the discipline and type of degree.">
<CAPTION>Programs Available</CAPTION>
<COLGROUP CLASS="program-discipline">
<COLGROUP CLASS="program-type" SPAN=5>
<THEAD>
<TR>
<TH SCOPE=col>Program</TH>
<TH SCOPE=col>Honors Co-op</TH>
<TH SCOPE=col>Honors Regular</TH>
<TH SCOPE=col>General Regular</TH>
<TH SCOPE=col>*Preprofessional or Professional</TH>
</TR>
</THEAD>
<TFOOT CLASS=footnote>
<TR>
<TD COLSPAN=5>
Many disciplines are also available as Minors and Joint
Honors programs.
</TD>
</TR>
<TR>
<TD COLSPAN=5>
* Preprofessional programs normally fulfull the academic
requirements for registration in the related professions.
</TD>
</TR>
</TFOOT>
<TBODY>
<TR>
<TD SCOPE=row>Computer Science</TD>
<TD>yes</TD>
<TD>yes</TD>
<TD>no</TD>
<TD>no</TD>
</TR>
...
</TBODY>
</TABLE>
In addition to the attributes common to most elements, TFOOT takes
presentational attributes for specifying the alignment of cell data. Since few
browsers support TFOOT, authors may wish to specify these attributes on the TR
or TD elements instead.
The ALIGN attribute specifies the horizontal alignment for each cell in the
row group. Possible values are left, center, right, justify, and char.
ALIGN=char aligns a cell's contents on the character given in the CHAR
attribute. The default value for the CHAR attribute is the decimal point of
the current language--a period in English. The CHAROFF attribute specifies
the offset to the first occurrence of the alignment character. The attribute's
value is a number in pixels or a percentage of the cell's width; CHAROFF="50%"
centers the alignment character horizontally in a cell.
The VALIGN attribute specifies the vertical position of a cell's contents.
Possible values are:
o top, which positions data at the top of the cell;
o middle, the default value, which centers the cell data vertically;
o bottom, which positions data at the bottom of the cell;
o baseline, which specifies that the first line of each cell in the row with
ALIGN=baseline should occur on a common baseline.
ΓòÉΓòÉΓòÉ 1.5.84. TH - Table header cell ΓòÉΓòÉΓòÉ
TH - Table Header Cell
Syntax
<TH>...</TH>
Attribute Specifications
o ROWSPAN= Number (rows spanned by the cell)
o COLSPAN= Number (columns spanned by the cell)
o HEADERS= IDREFS (list of header cells for current cell)
o ABBR= Text (abbreviation for header cell)
o SCOPE=[ row | col | rowgroup | colgroup ] (cells covered by header cell)
o AXIS= CDATA (category of header cell)
o ALIGN=[ left | center | right | justify | char ] (horizontal alignment)
o CHAR= Character (alignment character)
o CHAROFF= Length (alignment character offset)
o VALIGN=[ top | middle | bottom | baseline ] (vertical alignment)
o WIDTH= Pixels (cell width)
o HEIGHT= Pixels (cell height)
o NOWRAP (suppress word wrap)
o BGCOLOR= Color (cell background color)
o common attributes
Contents
Inline elements, block-level elements
Contained in
TR
The TH element defines a header cell in a table. TH elements are contained
within a TR element (a table row), which may also contain TD elements for
data cells. When a cell's contents act as both header information and table
data, TD should be used.
The ROWSPAN and COLSPAN attributes of TH specify the number of rows and the
number of columns, respectively, that are spanned by the cell. The default
value is 1. The special value 0 indicates that the cell spans all rows or
columns to the end of the table. The value 0 is ignored by most browsers, so
authors may wish to calculate the exact number of rows or columns spanned and
use that value.
The HEADERS attribute specifies the header cells that apply to the TH. The
value is a space-separated list of the header cells' ID attribute values. The
HEADERS attribute allows non-visual browsers to render the header information
for a given cell.
The ABBR attribute gives an abbreviated version of the cell's content. This
allows visual browsers to use the short form if space is limited, and
non-visual browsers can give a cell's header information in an abbreviated form
before rendering each cell.
The SCOPE attribute specifies the cells for which the TH element provides
header information. SCOPE is a simpler alternative to using HEADERS if the
arrangement of header cells is not complex. Possible values are as follows:
o row, when the TH provides header information for the rest of the row;
o col, when the TH provides header information for the rest of the column;
o rowgroup, when the TH gives header information for the rest of the row group
(i.e., the remaining cells of the THEAD, TFOOT, or TBODY);
o colgroup, when the TH gives header information for the rest of the column
group (i.e., the remaining cells of the COLGROUP).
The AXIS attribute provides a method of categorizing cells. The attribute's
value is a comma-separated list of category names. See the HTML 4.0
Recommendation's section on categorizing cells for an application of AXIS.
In addition to the attributes common to most elements, TH takes a number of
presentational attributes. Style sheets provide a more flexible way to suggest
a presentation for table cells, but TH's presentational attributes are more
widely supported by current browsers.
The ALIGN attribute specifies the horizontal alignment for the cell. Possible
values are left, center, right, justify, and char. ALIGN=char, poorly supported
among browsers, aligns a cell's contents on the character given in the CHAR
attribute. The default value for the CHAR attribute is the decimal point of
the current language--a period in English. The CHAROFF attribute specifies
the offset to the first occurrence of the alignment character. The attribute's
value is a number in pixels or a percentage of the cell's width; CHAROFF="50%"
centers the alignment character horizontally in a cell.
The VALIGN attribute specifies the vertical position of a cell's contents.
Possible values are:
o top, which positions data at the top of the cell;
o middle, the default value, which centers the cell data vertically;
o bottom, which positions data at the bottom of the cell;
o baseline, which specifies that the first line of each cell in the row with
ALIGN=baseline should occur on a common baseline.
The WIDTH, HEIGHT, NOWRAP, and BGCOLOR attributes are all deprecated in favor
of style sheets. WIDTH and HEIGHT suggest the cell's width and height in
pixels. The boolean NOWRAP attribute tells visual browsers to disable word
wrap for the cell, which can result in unnecessary horizontal scrolling
depending on the user's window width and font size.
The BGCOLOR attribute suggests a background color for the cell. The
combination of this attribute with < FONT COLOR=...> can leave invisible or
unreadable text on Netscape Navigator 2.x, which does not support BGCOLOR on
table elements. BGCOLOR is dangerous even on supporting browsers, since most
fail to override it when overriding other author-specified colors. Style sheets
provide a safer, more flexible method of specifying a table's background color.
ΓòÉΓòÉΓòÉ 1.5.85. THEAD - Table head ΓòÉΓòÉΓòÉ
THEAD - Table Head
Syntax
<THEAD>...</THEAD>
Attribute Specifications
o ALIGN=[ left | center | right | justify | char ] (horizontal alignment of
cells in group)
o CHAR= Character (alignment character for cells)
o CHAROFF= Length (alignment character offset)
o VALIGN=[ top | middle | bottom | baseline ] (vertical alignment of cells
in group)
o common attributes
Contents
One or more TR elements
Contained in
TABLE
The THEAD element defines a group of header rows in a table. A TABLE may
have one THEAD, which must follow any CAPTION, COL, or COLGROUP elements,
and precede the optional TFOOT and required TBODY elements.
By explicitly grouping header rows with THEAD, authors give browsers the
ability to include the header rows on each page of a printed, multi-page table,
as well as the ability to present a long table with a scrolling body and static
header rows. While few browsers currently support THEAD, it can be used with
no harm on non-supporting browsers.
The following example uses THEAD to group the two header rows of a table:
<TABLE SUMMARY="This table gives the character entity reference,
decimal character reference, and hexadecimal character
reference for 8-bit Latin-1 characters, as well as the
rendering of each in your browser.">
<COLGROUP>
<COLGROUP SPAN=3>
<COLGROUP SPAN=3>
<THEAD>
<TR>
<TH SCOPE=col ROWSPAN=2>Character</TH>
<TH SCOPE=col ROWSPAN=2>Entity</TH>
<TH SCOPE=col ROWSPAN=2>Decimal</TH>
<TH SCOPE=col ROWSPAN=2>Hex</TH>
<TH SCOPE=colgroup COLSPAN=3>Rendering in Your Browser</TH>
</TR>
<TR> <TH SCOPE=col>Entity</TH>
<TH SCOPE=col>Decimal</TH>
<TH SCOPE=col>Hex</TH> </TR>
</THEAD>
<TBODY>
<TR>
<TD SCOPE=row>non-breaking space</TD>
<TD> </TD>
<TD> </TD>
<TD> </TD>
<TD> </TD>
<TD> </TD>
<TD> </TD>
</TR>
...
</TBODY>
</TABLE>
In addition to the attributes common to most elements, THEAD takes
presentational attributes for specifying the alignment of cell data. Since few
browsers support THEAD, authors may wish to specify these attributes on the
TR, TH, or TD elements instead.
The ALIGN attribute specifies the horizontal alignment for each cell in the
row group. Possible values are left, center, right, justify, and char.
ALIGN=char aligns a cell's contents on the character given in the CHAR
attribute. The default value for the CHAR attribute is the decimal point of
the current language--a period in English. The CHAROFF attribute specifies
the offset to the first occurrence of the alignment character. The attribute's
value is a number in pixels or a percentage of the cell's width; CHAROFF="50%"
centers the alignment character horizontally in a cell.
The VALIGN attribute specifies the vertical position of a cell's contents.
Possible values are:
o top, which positions data at the top of the cell;
o middle, the default value, which centers the cell data vertically;
o bottom, which positions data at the bottom of the cell;
o baseline, which specifies that the first line of each cell in the row with
ALIGN=baseline should occur on a common baseline.
ΓòÉΓòÉΓòÉ 1.5.86. TITLE - Document title ΓòÉΓòÉΓòÉ
TITLE - Document Title
Syntax
<TITLE>...</TITLE>
Attribute Specifications
o internationalization attributes
Contents
Plain text (including entities)
Contained in
HEAD
The TITLE element gives the document's title. Each document must have exactly
one TITLE within the HEAD. TITLE contains plain text and entities; it may
not contain other markup.
A good TITLE should be short and specific to the document's content so that it
can be used as a title for a user's bookmark, a title for the display window on
visual browsers, and a link from a search engine. A suggested limit for the
number of characters in a TITLE is 60.
ΓòÉΓòÉΓòÉ 1.5.87. TR - Table row ΓòÉΓòÉΓòÉ
TR - Table Row
Syntax
<TR>...</TR>
Attribute Specifications
o ALIGN=[ left | center | right | justify | char ] (horizontal alignment of
cells in group)
o CHAR= Character (alignment character for cells)
o CHAROFF= Length (alignment character offset)
o VALIGN=[ top | middle | bottom | baseline ] (vertical alignment of cells
in group)
o BGCOLOR= Color (row background color)
o common attributes
Contents
One or more TH or TD elements
Contained in
THEAD, TFOOT, TBODY
The TR element defines a table row. TR elements must be contained within a
row group defined by THEAD, TFOOT, or TBODY. Since the start and end tags
of TBODY are optional when the table has one TBODY and no THEAD or TFOOT,
the simple table structure of HTML 3.2 is still valid:
<TABLE>
<TR>
<TH>Abbreviation</TH>
<TH>Long Form</TH>
</TR>
<TR>
<TD>AFAIK</TD>
<TD>As Far As I Know</TD>
</TR>
</TABLE>
TR contains TH or TD elements, which in turn contain the actual data of
the table. In addition to the attributes common to most elements, TR takes
presentational attributes for specifying the alignment of cells within the row
and the row's background color.
The ALIGN attribute specifies the horizontal alignment for each cell in the
row. Possible values are left, center, right, justify, and char. ALIGN=char
aligns a cell's contents on the character given in the CHAR attribute. The
default value for the CHAR attribute is the decimal point of the current
language--a period in English. The CHAROFF attribute specifies the offset to
the first occurrence of the alignment character. The attribute's value is a
number in pixels or a percentage of the cell's width; CHAROFF="50%" centers
the alignment character horizontally in a cell.
The VALIGN attribute specifies the vertical position of a cell's contents.
Possible values are:
o top, which positions data at the top of the cell;
o middle, the default value, which centers the cell data vertically;
o bottom, which positions data at the bottom of the cell;
o baseline, which specifies that the first line of each cell in the row with
ALIGN=baseline should occur on a common baseline.
The deprecated BGCOLOR attribute suggests a background color for the row.
The combination of this attribute with < FONT COLOR=...> can leave invisible
or unreadable text on Netscape Navigator 2.x, which does not support BGCOLOR
on table elements. BGCOLOR is dangerous even on supporting browsers, since
most fail to override it when overriding other author-specified colors. Style
sheets provide a safer, more flexible method of specifying a row's background
color.
ΓòÉΓòÉΓòÉ 1.5.88. TT - Teletype text ΓòÉΓòÉΓòÉ
TT - Teletype Text
Syntax
<TT>...</TT>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The TT element suggests that text be rendered as teletype or monospaced text.
In most cases, use of a phrase elemens such as CODE, SAMP, or KBD is more
appropriate since these elements express the meaning of the text more clearly.
Style sheets should be used to complement or replace instances of TT. For
example, replacing
<H1><TT>My heading</TT></H1>
with
<H1>My heading</H1>
and
H1 { font-family: monospace }
in a style sheet allows the author to change the presentation of all H1
elements in an entire site by changing just one line in the style sheet.
ΓòÉΓòÉΓòÉ 1.5.89. U - Underlined text ΓòÉΓòÉΓòÉ
U - Underlined Text
Syntax
<U>...</U>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The U element, deprecated in HTML 4.0, suggests that text be rendered as
underlined text. In most cases, use of a phrase elemens such as CITE or STRONG
is more appropriate since such elements express the meaning of the text more
clearly.
Style sheets should be used to complement or replace instances of U. For
example, replacing
<H1><U>My heading</U></H1>
with
<H1>My heading</H1>
and
H1 { text-decoration: underline }
in a style sheet allows the author to change the presentation of all H1
elements in an entire site by changing just one line in the style sheet.
ΓòÉΓòÉΓòÉ 1.5.90. UL - Unordered list ΓòÉΓòÉΓòÉ
UL - Unordered List
Syntax
<UL>...</UL>
Attribute Specifications
o TYPE=[ disc | square | circle ] (bullet style)
o COMPACT (compact display)
o common attributes
Contents
One or more LI elements
Contained in
APPLET, BLOCKQUOTE, BODY, BUTTON, CENTER, DD, DEL, DIV, FIELDSET,
FORM, IFRAME, INS, LI, MAP, NOFRAMES, NOSCRIPT, OBJECT, TD, TH
The UL element defines an unordered list. The element contains one or more
LI elements that define the actual items of the list.
Unlike with an ordered list ( OL), the items of an unordered list have no
sequence. In theory, users should be able to change the order of items in an
unordered list (e.g., alphabetizing them).
Visual browsers typically render UL with a bullet preceding each list item,
but authors can suggest various presentations using style sheets. The
list-style property of Cascading Style Sheets allows authors to suppress
bullets, use images as list item markers, and more.
The deprecated TYPE attribute of UL suggests the bullet style on visual
browsers. Possible values are as follows:
o disc (a filled-in circle)
o square (a square outline)
o circle (a circle outline)
The bullet style on an individual list item can be suggested using the TYPE
attribute of LI. The list-style-type property of CSS provides greater
flexibility in suggesting bullet styles.
The deprecated COMPACT attribute suggests that visual browsers render the
list compactly, perhaps with reduced spacing between items. This attribute is
not well supported among browsers.
ΓòÉΓòÉΓòÉ 1.5.91. VAR - Variable ΓòÉΓòÉΓòÉ
VAR - Variable
Syntax
<VAR>...</VAR>
Attribute Specifications
o common attributes
Contents
Inline elements
Contained in
Inline elements, block-level elements
The VAR element is used to markup variables or program arguments. Visual
browsers typically render VAR as italic text, but authors can suggest a
rendering using style sheets. Since VAR is a structural element, it carries
meaning, making it preferable to font style elements such as I when marking
up variables.
Example:
<P>Versions of HTML are typically numbered in an
<VAR>x</VAR>.<VAR>x</VAR> format.</P>
ΓòÉΓòÉΓòÉ 1.6. Entities ΓòÉΓòÉΓòÉ
Entities
Character entity references, or entities for short, provide a method of
entering characters that cannot be expressed in the document's character
encoding or that cannot easily be entered on a keyboard. Entities are
case-sensitive and take the form &name;. Examples of entities include ©
for the copyright symbol and Α for the Greek capital letter alpha.
In addition to entities, authors can use numeric character references. While
entities are limited to a subset of Unicode characters, numeric character
references can specify any character. Numeric character references may be given
in decimal or hexadecimal, though browser support is stronger for decimal
references. Decimal references are of the form number; while hexadecimal
references take the case-insensitive form number;. Examples of numeric
character references include © or © for the copyright symbol, Α
or Α for the Greek capital letter alpha, and ا or ا for the
Arabic letter ALEF.
Note that hexadecimal character references will cause errors with current
validators since these references are defined in a recent revision to the SGML
standard that is not yet supported by validators.
The following documents feature tables of the character entity references in
HTML 4.0, along with the numeric character reference in decimal and
hexadecimal. A rendering of each character reference is provided so that users
may check their browsers' compliance.
o Latin-1 Entities
o Symbols and Greek Letters
o Other Special Characters
ΓòÉΓòÉΓòÉ 1.6.1. Latin-1 Entities ΓòÉΓòÉΓòÉ
Latin-1 Entities
¡ ¡ ¡
¢ ¢ ¢
£ £ £
¤ ¤ ¤
¥ ¥ ¥
¦ ¦ ¦
§ § §
¨ ¨ ¨
© © ©
ª ª ª
« « «
¬ ¬ ¬
® ® ®
¯ ¯ ¯
° ° °
± ± ±
² ² ²
³ ³ ³
´ ´ ´
µ µ µ
¶ ¶ ¶
· · ·
¸ ¸ ¸
¹ ¹ ¹
º º º
» » »
¼ ¼ ¼
½ ½ ½
¾ ¾ ¾
¿ ¿ ¿
À À À
Á Á Á
  Â
à à Ã
Ä Ä Ä
Å Å Å
Æ Æ Æ
Ç Ç Ç
È È È
É É É
Ê Ê Ê
Ë Ë Ë
Ì Ì Ì
Í Í Í
Î Î Î
Ï Ï Ï
Ð Ð Ð
Ñ Ñ Ñ
Ò Ò Ò
Ó Ó Ó
Ô Ô Ô
Õ Õ Õ
Ö Ö Ö
× × ×
Ø Ø Ø
Ù Ù Ù
Ú Ú Ú
Û Û Û
Ü Ü Ü
Ý Ý Ý
Þ Þ Þ
ß ß ß
à à à
á á á
â â â
ã ã ã
ä ä ä
å å å
æ æ æ
ç ç ç
è è è
é é é
ê ê ê
ë ë ë
ì ì ì
í í í
î î î
ï ï ï
ð ð ð
ñ ñ ñ
ò ò ò
ó ó ó
ô ô ô
õ õ õ
ö ö ö
÷ ÷ ÷
ø ø ø
ù ù ù
ú ú ú
û û û
ü ü ü
ý ý ý
þ þ þ
ÿ ÿ ÿ
ΓòÉΓòÉΓòÉ 1.6.2. Symbols and Greek Letters ΓòÉΓòÉΓòÉ
Symbols and Greek Letters
ƒ ƒ ƒ
Α Α Α
Β Β Β
Γ Γ Γ
Δ Δ Δ
Ε Ε Ε
Ζ Ζ Ζ
Η Η Η
Θ Θ Θ
Ι Ι Ι
Κ Κ Κ
Λ Λ Λ
Μ Μ Μ
Ν Ν Ν
Ξ Ξ Ξ
Ο Ο Ο
Π Π Π
Ρ Ρ Ρ
Σ Σ Σ
Τ Τ Τ
Υ Υ Υ
Φ Φ Φ
Χ Χ Χ
Ψ Ψ Ψ
Ω Ω Ω
α α α
β β β
γ γ γ
δ δ δ
ε ε ε
ζ ζ ζ
η η η
θ θ θ
ι ι ι
κ κ κ
λ λ λ
μ μ μ
ν ν ν
ξ ξ ξ
ο ο ο
π π π
ρ ρ ρ
ς ς ς
σ σ σ
τ τ τ
υ υ υ
φ φ φ
χ χ χ
ψ ψ ψ
ω ω ω
ϑ ϑ ϑ
ϒ ϒ ϒ
ϖ ϖ ϖ
• • •
… … …
′ ′ ′
″ ″ ″
‾ ‾ ‾
⁄ ⁄ ⁄
ℑ ℑ ℑ
℘ ℘ ℘
ℜ ℜ ℜ
™ ™ ™
ℵ ℵ ℵ
← ← ←
↑ ↑ ↑
→ → →
↓ ↓ ↓
↔ ↔ ↔
↵ ↵ ↵
⇐ ⇐ ⇐
⇑ ⇑ ⇑
⇒ ⇒ ⇒
⇓ ⇓ ⇓
⇔ ⇔ ⇔
∀ ∀ ∀
∂ ∂ ∂
∃ ∃ ∃
∅ ∅ ∅
∇ ∇ ∇
∈ ∈ ∈
∉ ∉ ∉
∋ ∋ ∋
∏ ∏ ∏
∑ ∑ ∑
− − −
∗ ∗ ∗
√ √ √
∝ ∝ ∝
∞ ∞ ∞
∠ ∠ ∠
∧ ∧ ∧
∨ ∨ ∨
∩ ∩ ∩
∪ ∪ ∪
∫ ∫ ∫
∴ ∴ ∴
∼ ∼ ∼
≅ ≅ ≅
≈ ≈ ≈
≠ ≠ ≠
≡ ≡ ≡
≤ ≤ ≤
≥ ≥ ≥
⊂ ⊂ ⊂
⊃ ⊃ ⊃
⊄ ⊄ ⊄
⊆ ⊆ ⊆
⊇ ⊇ ⊇
⊕ ⊕ ⊕
⊗ ⊗ ⊗
⊥ ⊥ ⊥
⋅ ⋅ ⋅
⌈ ⌈ ⌈
⌉ ⌉ ⌉
⌊ ⌊ ⌊
⌋ ⌋ ⌋
〈 〈 〈
〉 〉 〉
◊ ◊ ◊
♠ ♠ ♠
♣ ♣ ♣
♥ ♥ ♥
♦ ♦ ♦
ΓòÉΓòÉΓòÉ 1.6.3. Other Special Characters ΓòÉΓòÉΓòÉ
Other Special Characters
" " "
& & &
< < <
> > >
Œ Œ Œ
œ œ œ
Š Š Š
š š š
Ÿ Ÿ Ÿ
ˆ ˆ ˆ
˜ ˜ ˜
– – –
— — —
‘ ‘ ‘
’ ’ ’
‚ ‚ ‚
“ “ “
” ” ”
„ „ „
† † †
‡ ‡ ‡
‰ ‰ ‰
‹ ‹ ‹
› › ›
€ € €
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
CDATA
Attribute values of type CDATA are made up of a sequence of characters that may
include entities. Line feeds are ignored while each carriage return and tab is
replaced with a space. Browsers may ignore leading and trailing whitespace
within the attribute value.
CDATA attribute values are typically case-sensitive, though this is not the
case with all attributes that take CDATA values.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
ID and NAME
Attribute values of type ID and NAME must begin with a letter in the range A-Z
or a-z and may be followed by letters (A-Za-z), digits (0-9), hyphens ("-"),
underscores ("_"), colons (":"), and periods ("."). These values are case-sensitive.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
IDREF and IDREFS
IDREF and IDREFS values refer to values of other elements' ID attributes. An
IDREF value is a single ID while an IDREFS value is a space-separated list of
IDs. IDREF and IDREFS are case-sensitive.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
Number
Number attribute values are numbers made of at least one digit in the range 0-9.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
Text
Text attribute values are CDATA values intended to be human readable strings.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
URI
URI attribute values are Uniform Resource Identifiers (URIs), as defined in the
URI Internet-Draft, a work-in-progress that is expected to replace RFC 1738 and
RFC 1808.
URI attribute values may include full URIs such as http://www.htmlhelp.com/. as
well as relative URIs such as foo.html and ../foo/.
While parts of a URI may be case-insensitive, in general URI values are case-sensitive.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
Color
Color attribute values give a color definition. The value can be any
hexadecimal number, specified according to the sRGB color space, or one of
sixteen color names. Hexadecimal numbers must be prefixed by a "#" character.
The case-insensitive color names and their sRGB values are as follows:
Color Name sRGB Value
Black #000000
Silver #C0C0C0
Gray #808080
White #FFFFFF
Maroon #800000
Red #FF0000
Purple #800080
Fuchsia #FF00FF
Green #008000
Lime #00FF00
Olive #808000
Yellow #FFFF00
Navy #000080
Blue #0000FF
Teal #008080
Aqua #00FFFF
Note that the hexadecimal form is better supported than the color names for the
color attributes of BODY.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
Pixels
These attribute values are integers that represent a number of pixels.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
Length
Length attribute values may be either an integer--interpreted as a number of
pixels--or a percentage of the horizontal or vertical space. The value 50%
means half the available space while 50 means 50 pixels.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
MultiLength and MultiLengths
MultiLength attribute values may be an integer in pixels, a percentage of the
horizontal or vertical space, or a relative length expressed as i* where i is
an integer. In allotting space, a browser first allots pixel and percentage
lengths, then divides the remaining space among all elements with a relative
length. An element with a length of 3* will be allotted three times the space
of an element with length 1*. The value * is equivalent to 1* and is often used
to mean "fill the remaining space."
A MultiLengths value is a comma-separated list of MultiLength values.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
ContentType and ContentTypes
These attribute values are content types (also known as media types or MIME
types) of a linked or embedded resource. Values of type ContentType give a
single content type while values of type ContentTypes give a comma-separated
list of content types. Content types are case-insensitive.
Commonly used content types include text/html, image/jpeg, model/vrml,
video/quicktime, application/java, text/css, and text/javascript. Many common
content types are registered at the IANA.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
LanguageCode
Attribute values of type LanguageCode specify a language code according to RFC
1766. Examples of language codes include en for English, en-US for American
English, and ja for Japanese. Whitespace is not allowed in the language code,
which is case-insensitive.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
Charset and Charsets
These attribute values specify character encodings of linked resources. Values
of type Charset give a single character encoding while values of type Charsets
give a space- and/or comma-separated list of character encodings. Character
encodings are case-insensitive.
Examples of character encodings include ISO-8859-1, SHIFT_JIS, and UTF-8. A
list of registered character encodings is available at the IANA.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
Character
Character attribute values take a single Unicode character. The character may
be specified with an entity.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
Datetime
Datetime attribute values give a date and time in the format
YYYY-MM-DDThh:mm:ssTZD where YYYY is a four-digit year, MM is a two-digit month
(01 through 12), DD is a two-digit day (01 through 31), hh is a two-digit
hour(00 through 23), mm is a two-digit minute (00 through 59), ss is a
two-digit second (00 through 59), and TZD is the time zone designator. Note
that the T separating the date from the time must appear literally and is
case-sensitive.
The time zone designator may be one of the following:
o Z (case-sensitive), which indicates Universal Coordinated Time (UTC,
basically the same as GMT);
o +hh:mm, the time ahead of UTC in hours and minutes;
o -hh:mm, the time behind UTC in hours and minutes.
If any of the two-digit components of the Datetime value are unknown, 00 should
be used.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
LinkTypes
Attribute values of type LinkTypes give a space-separated list of link types. A
link type is case-insensitive and may not contain whitespace. Each link type
may be used any number of times in a given document.
While link types are case-insensitive, the Lynx browser will render LINK
elements with the same case as is given in the REL or REV attribute. Authors
should therefore be consistent in their case, and may wish to capitalize the
first letter while using lowercase for the rest.
The following link types are defined in HTML 4.0, though authors may use other
link types. The Made link type, widely used as <LINK REV=Made
HREF="mailto:liam@htmlhelp.com"> to provide a contact link for the document
author, is notably missing from the list of link types defined in HTML 4.0.
o Alternate specifies an alternate version of the document. When used with the
LINK element's HREFLANG attribute, this value implies a translation of the
document. When used with LINK's MEDIA attribute, a media-specific version
(e.g., for printing) is implied.
o StyleSheet specifies an external style sheet for the document. This link type
can be combined with the Alternate link type to define an alternate style
sheet for the user to choose.
o Start specifies the first document in a collection.
o Next specifies the next document in a suggested sequence of reading. Browsers
such as WebTV will preload documents identified as "next" to improve the
perceived load time.
o Prev specifies the previous document in a suggested sequence of reading.
o Contents specifies a table of contents for the document.
o Index gives an index for the document.
o Glossary gives a glossary of terms used in the document.
o Copyright specifies a document with copyright information.
o Chapter specifies the chapter of a collection of documents.
o Section specifies the section of a collection of documents.
o Subsection specifies a subsection of a collection of documents.
o Appendix gives an appendix for the collection of documents.
o Help specifies a help document.
o Bookmark refers to a key related document. The TITLE attribute provides a
label for the bookmark.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
MediaDesc
Attribute values of type MediaDesc are media descriptors--a comma-separated
list of media for which the linked resource is tailored. Media descriptors are
case-sensitive.
The following media descriptors are defined in HTML 4.0:
o screen (the default), for non-paged computer screens;
o tty, for fixed-pitch character grid displays (such as the display used by
Lynx);
o tv, for television-type devices with low resolution and limited
scrollability;
o projection, for projectors;
o handheld, for handheld devices (characterized by a small, monochrome display
and limited bandwidth);
o print, for output to a printer;
o braille, for braille tactile feedback devices;
o aural, for speech synthesizers;
o all, for all devices.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
Script
Script attribute values are client-side scripts, typically a function call or a
few short statements. The value may contain entities (e.g., ").
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
StyleSheet
Attribute values of type StyleSheet are style sheet data. The value may contain entities.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
FrameTarget
Attribute values of type FrameTarget must begin with a letter in the range A-Z
or a-z, with the exception of the following special values that begin with an
underscore:
o _blank renders the link in a new, unnamed window
o _self renders the link in the current frame (useful for overriding a BASE
TARGET)
o _parent renders the link in the immediate FRAMESET parent
o _top renders the link in the full, unframed window
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
ID
The ID attribute uniquely identifies an element within a document. No two
elements can have the same ID value in a single document. The attribute's value
must begin with a letter in the range A-Z or a-z and may be followed by letters
(A-Za-z), digits (0-9), hyphens ("-"), underscores ("_"), colons (":"), and
periods (".").
The following example uses the ID attribute to identify each of the first two
paragraphs of a document:
<P ID=firstp>My first paragraph.</P>
<P ID=secondp>My second paragaph.</P>
The paragraphs in the example could have style rules associated with them
through their ID attributes. The following Cascading Style Sheet defines unique
colors for the two paragraphs:
P#firstp {
color: navy;
background: transparent
}
P#secondp {
color: black;
background: transparent
}
The paragraphs in the initial example could also be used as a target anchor for
links:
<P>See <A HREF="#firstp">the opening paragraph</A>
for more information.</P>
Note that most browsers do not support the ID attribute for link anchors. For
current browsers, authors should use <A NAME>...</A> within the element instead
of ID.
Since ID and NAME share the same name space, authors cannot use the same value
for an ID attribute and a NAME attribute in the same document. Also note that
while NAME may contain entities, the ID attribute value may not.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
CLASS
The CLASS attribute specifies the element to be a member of one or more
classes. Classes allow authors to define specific kinds of a given element. For
example, an author could use <CODE CLASS=Java> when giving Java code and <CODE
CLASS=Perl> when giving Perl code.
Unlike with the ID attribute, any number of elements can share the same class.
An element may also belong to multiple classes; the CLASS attribute value is a
space-separated list of class names.
Note that most current browsers do not support multiple classes. Such browsers
typically ignore a CLASS attribute that specifies multiple classes.
The CLASS attribute is particularly useful when combined with style sheets .
For example, consider the following navigation bar:
<DIV CLASS=navbar>
<P><A HREF="/">Home</A> | <A HREF="./">Index</A> | <A
HREF="/search.html">Search</A></P>
<P><A HREF="/"><IMG SRC="logo.gif" ALT="" TITLE="WDG
Logo"></A></P>
</DIV>
This example's use of the CLASS attribute allows style rules to easily be
added. The following Cascading Style Sheet suggests a presentation for the
preceding example:
.navbar {
margin-top: 2em;
padding-top: 1em;
border-top: solid thin navy
}
.navbar IMG { float: right }
@media print {
.navbar { display: none }
}
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
STYLE
The STYLE attribute allows authors to specify style rules inline for a single
occurrence of an element. An example follows:
<P>A popular font for on-screen reading is
<SPAN STYLE="font-family: Verdana">Verdana</SPAN>.</P>
When the STYLE attribute is used, a default style sheet language must be
specified for the document by setting the Content-Style-Type HTTP header to the
media type of the style sheet language. The previous example could use the
following META element in the document's HEAD:
<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">
In most cases, use of the CLASS or ID attributes is a better choice than using
STYLE since ID and CLASS can be selectively applied to different media and
since they provide a separation of content and presentation that often
simplifies maintenance.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
TITLE
The TITLE attribute provides a title for an element and is commonly implemented
as a "tooltip" on visual browsers, though many browsers lack support for TITLE.
The attribute is most useful with A, LINK, IMG, and OBJECT elements, where it
provides a title for the linked or embedded resource. Some examples follow:
o
<A HREF="mailto:liam@htmlhelp.com"
TITLE="Feedback on HTML 4.0 Reference">
liam@htmlhelp.com</A>
o
<A HREF="http://www-genome.wi.mit.edu/ftp/pub/software/WWW/cgi_docs.html"
TITLE="CGI.pm - a Perl5 CGI Library">CGI.pm</A>
o <LINK REL=Alternate HREF="index.fr.html" HREFLANG=fr LANG=fr
TITLE="Version franЗaise">
o
<OBJECT CLASSID="java:Yahtzee.class"
CODETYPE="application/java" WIDTH=400 HEIGHT=250
STANDBY="Ready to play Yahtzee?" TITLE="My Yahtzee Game">
<IMG SRC="yahtzee.gif" ALT="" TITLE="A Yahtzee animation">
Yahtzee is my <EM>favorite</EM> game!
</OBJECT>
TITLE is also helpful with the ABBR and ACRONYM elements to provide the long
form of the abbreviation. Examples:
o He weighs 180 <ABBR TITLE=pounds>lbs.</ABBR>
o <ABBR TITLE="Parti QuВbВcois" LANG=fr-CA>PQ</ABBR>
o <ACRONYM TITLE="North Atlantic Treaty Organization">NATO</ACRONYM>
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
LANG
The LANG attribute specifies the language of an element's attribute values and
its content, including all contained elements that do not specify their own
LANG attribute. While the LANG attribute is not widely supported, its use may
help search engines index a document by its language while allowing speech
synthesizers to use language-dependent pronunciation rules. As well, visual
browsers can use the language's proper quotation marks when rendering the Q
element.
The attribute value is case-insensitive, and should be specified according to
RFC 1766; examples include en for English, en-US for American English, and ja
for Japanese. Whitespace is not allowed in the language code.
Use of the LANG attribute also allows authors to easily change the style of
text depending on the language. For example, a bilingual document may have one
language in italics if rendered visually or a different voice if rendered
aurally. The HTML of such a document might be as follows:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN"
"http://www.w3.org/TR/REC-html40/strict.dtd">
<TITLE>Welcome - Bienvenue</TITLE>
<H1>
<SPAN LANG=en>Welcome</SPAN> -
<SPAN LANG=fr>Bienvenue</SPAN>
</H1>
<P LANG=en>This paragraph is in English.</P>
<P LANG=fr>Ce paragraphe est en franЗais.</P>
...
A document's primary language may be set using the LANG attribute on the HTML
element, or, alternatively, by using the Content-Language HTTP header.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
DIR
The DIR attribute specifies the directionality of text--left-to-right (DIR=ltr,
the default) or right-to-left (DIR=rtl). Characters in Unicode are assigned a
directionality, left-to-right or right-to-left, to allow the text to be
rendered properly. For example, while English characters are presented
left-to-right, Hebrew characters are presented right-to-left.
Unicode defines a bidirectional algorithm that must be applied whenever a
document contains right-to-left characters. While this algorithm usually gives
the proper presentation, some situations leave directionally neutral text and
require the DIR attribute to specify the base directionality.
Text is often directionally neutral when there are multiple embeddings of
content with a different directionality. For example, an English sentence that
contains a Hebrew phrase that contains an English quotation would require the
DIR attribute to define the directionality of the Hebrew phrase. The Hebrew
phrase, including the English quotation, should be contained within a SPAN
element with DIR=rtl.
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www..w3.org/TR/RED-html40/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://charts.unicode.org/Unicode.charts/normal/Unicode.html
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.unicode.org/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.htmlhelp.com/reference/wilbur/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.htmlhelp.com/design/frames/whatswrong.html
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.htmlhelp.com/design/frames/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.netscaape.com/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.ics.uci.edu/pub/ietf/uri/draft-fielding-uri-syntax-02.txt
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://ds.internic.net/rfc/rfc1738.txt
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://ds.internic.net/rfc/rfc1808.txt
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
ftp://ftp.isi.edu/in-notes/iana/aggignments/media-types/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://ds.internic.net/rfc/rfc1766.txt
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
ftp://ftp.isi.edu/in-notes/iana/assignments/character-sets
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://lynx.browser.org/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://validator.w3.org/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://ds.internic.net/rfc/rfc1867.txt
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.w3.org/TR/PR-CSS2/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.w3.org/TR/PR-CSS2/aural.html#propdef-speak
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://java.sun.com/product/jdk/1.1/docs/guide/jar/index
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://java.sun.com/product/jdk/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.htmlhelp.com/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.stack.nl/%7Egalactus/html/url.html
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.mscr.olemiss.ecu/%7Emudws/font.html
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.netscape.com/navigator/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.cgi-resources.com/Programs_and_Scripts/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.cgi-resources.com/Programs_and_Scripts/Remotely_Hosted/Form_Processing/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.htmlhelp.com/tools/cg-eye/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www-genome.wi.mit.edu/ftp/pub/software/WWW/cgi_docs.html
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.htmlhelp.com/design/frames/faq/noborder.html
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www..w3.org/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://wwww3.org/Metadata/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.cdrom.com/pub/png/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.htmlhelp.com/feature/art3.htm
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://hoohoo/ncsa/uiuc/edu/docs/tutorials/imagemapping.html
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.htmlhelp.com/feature/art3c.htm
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://info.webcrawler.com/mak/projects/robots/exclusion/html#robotstxt
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.htmlhelp.com/design/frames/guidelines/auto-noframes.html
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http://home.netscape.com/assist/net-sites/new_html3_prop.html#Embed
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.microsoft.com/msdn/sdk/inetsdk/help/dhtml/references/html/bgsound/htm
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http://www.apple.com/quicktime/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.netscape.com/comprod/products/navigator/version_3.0/multimedia/audio/index.html
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.microsoft.com/ie/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.operasoftware.com/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.w3.org/TR/PR-math/
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.w3.org/TR/PR-CSS2/tables.html
ΓòÉΓòÉΓòÉ <hidden> ΓòÉΓòÉΓòÉ
http://www.w3.org/TR/REC-html40/
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