Mike
Wed Jun 21 16:20:07 CDT 2006
MP asked:
I need some recommendations on using "Alt" tags
1. They are not "required" correct"
2. Best practice is to use them though?
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Steve replied:
The alt tag is for text. You enter a short text description
of the image, which is what
appears when a mouse moves over the image.
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Murray corrected Steve:
Incorrect-
alt ATTRIBUTE is for accessability purposes. Only IE shows
the text when you
mouse over it. All modern browsers follow the W3 guidelines
for it - and wait for the
title attribute. If you have a title attribute *AND* an
alt attribute, then IE will
correctly only display the title attribute's contents on
rollover....
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Steve replied:
Correct
However, if the alt tag is missing the page won't validate.
Also, in EWD and SP-D if the alt tag is missing or blank, it
will fail on the
compatibility check.
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My turn.....
The ALT attribute is not required for a webpage to work. It
is required for it to pass
any type of validation though, as the standards for web
developement call for it.
This is due to accessibilty purposes- many people do not
have images shown for
various reasons, and the visual impaired people cannot see
them. This is where the
ALT attribute comes in. It is used as a placeholder for the
images when not displayed
or when the image is still downloading. TTS engines (screen
readers) also will read the
ALT information to the visually impaired.
MS programmed into IE the ability for the ALT information to
work as a tool tip if
there is no TITLE attribute present.
Sample:
<img src="Image_URL" alt="placeholder or text variant"
title="Tooltip aka Popup information">
The w3c standards really don't care about the ALT content,
and will validate alt="".
The accessibility standards (eg Sec508) which specifically
are looking for the ALT
information want a minimum length of 7 characters and a
maximum length of 81.
They should also be unique on the page.
Added benefits of using the Alt & Title attrbutes is Search
Engine Optimization. The
search engines will index the information from the
attributes also.