Topic:
the optional <BASE> tag normally occurs within the <HEAD> ... </HEAD> of an HTML document, and provides the URL basis for subsequent relative URL references within the body of the document.
HREF="URL"
The fully-qualified URL for the current document is required here.
<BASE> is legal within:
<HEAD>
No additional markup can be used within <BASE>
Whenever you build complex, multi-page collections, it's a good idea to use the <BASE> tag in each page, and to build a directory structure that's easy to use and navigate.
<BASE HREF="http://www.outer.net/html4dum/html4dum.htm">