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[Fwd: Server-Side Image Maps]

From: Ian Jacobs <ij@w3.org>
Date: Wed, 14 Oct 1998 10:33:28 -0400
Message-ID: <3624B638.B5997A34@w3.org>
To: w3c-wai-ua@w3.org
Hello,

I thought the UA WG might find this interesting.

 - Ian
-- 
Ian Jacobs (jacobs@w3.org) 
Tel/Fax: (212) 684-1814 
http://www.w3.org/People/Jacobs

attached mail follows:


WRT to the follow comment in the HTML4.0 spec:
 http://www.w3.org/TR/REC-html40/

> 13.2 Including an image: the IMG element
>
>  <!-- To avoid problems with text-only UAs as well as
>    to make image content understandable and navigable
>    to users of non-visual UAs, you need to provide
>    a description with ALT, and avoid server-side image maps -->

This is a common misconception of server-side image maps resulting from
a number of popular, but very poor server-side image map processors.

The original design (speaking as the original designer of ISMAP :) was that if
the client
did not/could not support maps that it would send a request to the server with
NO temporal/spatial information would would then trigger an approriate response
from the server (e.g., a menu of the choices or anything else the designer
could dream
up).  This gives the page author a lot of desirable flexibility.  For example:

     <A HREF="http://webhost/smart-image-mapper"><IMG SRC="imagefile" ALT="see
menu"></A>

     On a Visual UA would fetch "imagefile" and send spatial coordinates to
smart-image-mapper

     On a non-Visual UA would fetch "smart-image-mapper" with no coordinate
data and display
           the result in-line (if it can) otherwise it would present the ALT
text as a link which would
          fetch "smart-image-mapper" with no spatial coordinate data (which is
expected to
          generate an appropriate page).

It really sucks that so many image-map clients are broken and do not generate
pages for
"null" coordinates.  Perhaps we need to amend the spec to include a hint to web
browsers
about what they can expect to find, ISMAP could have an optional value:
 <A HREF="xxx"><IMG SRC="..." ISMAP>  <!-- unknown, prolly
broken -->
 <A HREF="xxx"><IMG SRC="..." ISMAP="link">  <!-- prefer a
link to xxx -->
 <A HREF="xxx"><IMG SRC="..." ISMAP="inline"> <!-- prefer to
inline output from xxx -->
Received on Wednesday, 14 October 1998 10:31:12 GMT

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