The MAP element was first introduced in the Client Side Image Map
proposal (an HTML Working Draft from Spry.) It was very quickly adopted
in browsers and then in the HTML 3.2 recommendation. MAP is the
containing element of a grouping of shape-link identification pairs (the
AREA element) used to identify image map
linking destinations with geometric regions on an image. This is accomplished
via an HTML encoding system, rather than the older, more time consuming ISMAP
method which requires an extra HTTP request and server-side processing map file.
The Client-side image map model can be made backward compatible with the old ISMAP
model by specifying the USEMAP attribute in the IMG
element where an ISMAP attribute is also present. The USEMAP attribute takes
as its value the URL of a Client Side Map specification. The URL specified can
either be in the current or an external file.
This attribute behaves the same as the A NAME attribute in defining
a destination within a document. It specifies the map location
within a file for reference by the IMG USEMAP attribute. They are
referenced in the IMG USEMAP attribute as either
"#mapname" [map is in the
current file] or "file/name#mapname"
[map location is in an external file] as appropriate.
DTD Note: The content model listed above is valid
as of HTML 4.01; in HTML 4.0 and previous standards, the only content allowed
in a MAP element was an AREA element. Luckily, most browsers already
support this new DTD content model.
It is usually a good idea to include an ISMAP as an alternative to
Client Side Image maps, but authors sometimes may not have access to
set up map files on their host machines. In this case especially, and in
general, a THIRD alternative should be authored to allow navigation
via text links for users that do not have image capability.
HTML 4.x+ recommends that authors use the ID attribute instead of the NAME
attribute wherever possible. ID is the accepted method moving forward and NAME is
actually removed as of XHTML 1.1.
Netscape has never supported external IDs/URLs in the USEMAP attribute
to the IMG element as per the specification (only internal anchors can
be used.) Internet Explorer supports external IDs/URLs from version 1.0
to 3.0, now it does not support them. Opera has supported external
IDs/URLs since version 3.0.
Netscape 6 betas 1 and 2 did not allow any displayable content inside
the MAP element. All other browsers have allowed this, and Netscape
6 beta 3+ does as well.