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Re: ALT and TITLE Clarification

From: Andrew Kirkpatrick <andrew_kirkpatrick@wgbh.org>
Date: Mon, 10 Jan 2005 12:31:16 -0500
To: Chris Ridpath <chris.ridpath@utoronto.ca>
Cc: Jim Thatcher <jim@jimthatcher.com>, WAI WCAG List <w3c-wai-gl@w3.org>, geoff_freed@wgbh.org
Message-id: <6E7B7FDC-632D-11D9-8EDC-0003937B30FE@wgbh.org>

> IMG element (not used as an anchor)
>
> 1) Alt text must be the empty string ("") if image is decorative.

I know that the language has been debated, but decorative may not be 
broad enough.  Images used for structuring the layout aren't really 
decorative, but they are commonly used (sigh).  "...if image lacks 
semantic significance"?

> 2) Alt text must convey the same information as the image. (from 
> guideline
> 1.1 SC 2)
> 3) Alt text must contain any text in the image unless the text is
> decorative. e.g image of blocks on http://www.btyahoo.com/internet (Are
> there any other cases where image text should not be in Alt text?)

Same as above, use of decorative is potentially problematic.

> pass condition:  rule 1 or (rule 2 and rule 3)
>
> IMG element (used within an anchor)
> 1) Alt text must be the empty string ("") if image is decorative. (This
> allows links that contain both an image and text avoid redundant link 
> text.

> Should we require that Alt text be empty if anchor contains both image 
> and
> text?)
No.  A combination of text and image-based information may be needed.

> 2) Alt text must describe the link destination.

Describe the link 'result'?  Not all links go somewhere.

> 3) Alt text must contain any text in the image unless the text is
> decorative.
>
> pass condition:  rule 1 or (rule 2 and rule 3)

I've been wondering if this isn't easier to think about in terms of the 
link.  The link content needs to identify the link "destination", and 
any image that is part of the content needs to adhere to the rules for 
all images. This would be a rule that would catch empty anchor elements 
(which an anchor containing only an image with null alt effectively 
is), but would allow anchors with combinations of text and images.
>
> For discussion, our ATRC site (http://atrc.utoronto.ca) contains 2 
> images
> used as anchors. The Alt text on the first image describes the link
> destination, does not describe the image and does not contain text 
> within
> image. The Alt text on the second image does not describe the link
> destination but does describe the image and does contain the image 
> text.
> Which image, or both, has correct Alt text?

Or neither?  I'd remove the "link to the" part of the first linked 
image, if not the "welcome page" aspect.  The latter part is just a 
stylistic decision, but the former represents unnecessary redundant 
information (screen reader: "link. link to the ATRC welcome page")

The W3C AAA conformance icon's alt should be (IMHO), "W3C WAI-AAA WCAG 
1.0".  It will be better when the abbreviations and acronyms in the 
icon's text can be expanded, but in this case users get the same info 
whether they are sighted or not. I'd put additional information into 
the title attribute, but currently would have a low expectation that it 
would be read.

AWK

-- 
Andrew Kirkpatrick
WGBH National Center for Accessible Media
125 Western Ave.
Boston, MA  02134
E-mail: andrew_kirkpatrick@wgbh.org
617.300.4420
Received on Monday, 10 January 2005 17:32:39 GMT

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