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>From tdowling at ohiolink.edu  Thu Feb 18 06:02:21 1999
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From: "Thomas Dowling" <tdowling at ohiolink.edu>
To: "Multiple recipients of list" <web4lib at webjunction.org>
Subject: Re: [WEB4LIB] "alt tags", etc
Date: Thu, 18 Feb 1999 09:02:08 -0500
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>Remember, I'm not "really" a techie, so could someone tell me what "alt
>tags" are, so that I know what I'm asking for?

I pointed out to Toni off list that one improvement she might make to her
very good site is to add ALT text to the images.

By way of an introduction or refresher, ALT text--technically, the value
of the IMG element's ALT attribute--provides a textual alternative to the
image.  This is needed by users whose browsers cannot, or are set not to,
display images.  Despite the behavior in current versions of Netscape and
MSIE, ALT text is not intended as a textual supplement displayed as a
pop-up or tool tip; it is an alternative to the image.

There are at least three categories of users who need this: people who
browse with no images either because of browser constraints or slow
connections; people with visual impairments who rely on screen reading
software or speaking browsers; and search engine spiders.  You'll have to
judge how much the first group means to you, but ignore the second and
third groups at your peril.  It is grossly unfair to make your site
inaccessible to the blind just to save a few keystrokes.  It may also be a
legal risk.  And the best looking site in the world may have trouble
getting visitors if Scooter. ArchitextSpider, Slurp, et al. "see" your
site as "Welcome to [].  Click any of the following: [] [] [] [] []."

' ALT="" ' is a permitted, and recommended, way to handle images that
don't really have a textual alternative, like bullets, spacers, and
divider lines.  ' ALT="" ' or ' ALT="*" ' is going to be a lot less
confusing to a screen reader than 'ALT="Blue Bullet"'.

Under the HTML 4.0 specification, the ALT attribute is required for every
IMG element.  It is also required for all AREA elements, and is
recommended for APPLET and INPUT type=IMAGE.

HTML 4.0 provides two other elements that IMG may employ to provide
textual information about images.  The TITLE attribute can be used on
almost any element to offer "advisory information about the element for
which it is set."  The LONGDESC attribute provides a link to another URL
that provides a lengthy description of the image.  So a fully decked out
IMG element might look like:

  <img src="artworks/mona_lisa.png"
    title="Leonardo's Mona Lisa"
    alt="1200dpi image of the Mona Lisa"
    longdesc="descriptions/mona_lisa.html">


It should be noted that no major browser supports LONGDESC yet.  IE does
display the TITLE as a tool tip, if it's present.  In lieu of LONGDESC
support, some sites use "d links"; see www.wgbh.org as an example.

I encourage all web authors to occasionally surf both their own sites and
the web in general with images off.  It's a pretty easy to discover the
barriers we inadvertently put up between our sites and some of our users.


Thomas Dowling
OhioLINK - Ohio Library and Information Network
tdowling at ohiolink.edu