The frame structure is not correct.

The tag <@> is used outside the form tag.

The end tag </@> is missing.

The character '>' must be written as '&gt;'. 

Inside <TEXTAREA> the tag <@> and any other tags are not allowed. 

The tag <@> is not allowed outside of <COLGROUP>.

The tag <@> is not allowed here. Inside tables it is allowed only in table cells (<TD> or <TH>).

The tag <@> is not allowed here.

The tag <@> is only allowed inside <FRAMESET>.

The tag <@> is used after the end of the document (after the tag </BODY>). 

Tags or text are not allowed here. The tag <@> is missing.

HTML comment is not correct. A valid comment must end with "-->".

<@> is not allowed inside <DL>.

<@> is only allowed inside <DL>.

<@> is only allowed inside lists.

<@> is only allowed inside table rows (<TR>).

<@> is only allowed inside tables.

<@> must not be nested.

<°> must not contain block level tags like <@>.

Inside <TITLE>...</TITLE> no other tags are allowed.

<@> is only allowed in the head of the file.

<@> is not allowed in the body of the file.

<TITLE> is missing.

<@> was used, though the body section has already started.

The contents of an frame alternative must be defined inside <NOFRAMES>.

</@> was used before some content is defined.

The start tag for </@> can't be found.

In tag <@> the value "°" is not valid for attribute "~". 

ID/NAME tokens must start with a letter an must contain only the characters A-Z, a-z, "_", "-", ":", ".".

Relative values must be given in the form "n*" (n is a number).

In the tag <@> the attribute "~" must only contain absolute pixel values.

The format of the date must be "YYYY-MM-DDThh:mm:ssTZD".

Color names are not allowed in HTML 2.0.

The tag <@> is not part of HTML 3.2.

The tag <@> is not part of HTML 2.

The tag <@> is only part of "HTML 4.0 Frameset". 

The tag <@> is an extension by Microsoft but not part of the official HTML standard.

The tag <@> is an extension by Netscape but not part of the official HTML standard.

The tag <@> was part of the HTML3.0 draft but it's not part of an official standard.

Since HTML 2.0 the tag <@> is no longer valid.

The tag <@> is not part of "HTML 4.0 Strict". 

In tag <@> the attribute "~" contains too many characters.

In tag <@> the attribute "~" must define a character. 

A color definition must contain exactly hex digits.

The color name "°" is not valid. 

Only digits are allowed in the value of the attribute "~".

The trailing ';' is missing in the definition "°". 

The definition "°" contains invald characters.

In the tag <@> the attribute "~" is not allowed.

The attribute "°" is not part of HTML. 

The end tag </@> is not defined. 

The end tag </°> is not part of HTML. 

The tag <°> is not part of HTML 4.0.

In the tag <@> white space is missing as separator after the attribute "~". 

The character '<' must be written as '&lt;'. 

Invalid characters in tag or attributes.

In the tag <@> the value of attribute "~" is missing. 

Attributes are not allowed in end tags. 

The HTML file contains invald characters.