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WCAG 2.0 Comment Submission

From: WCAG 2.0 Comment Form <nobody@w3.org>
Date: Wed, 23 May 2007 05:36:29 +0000 (GMT)
To: public-comments-wcag20@w3.org
Message-Id: <20070523053629.65C63BDA8@w3c4.w3.org>

Name: Jason White
Email: jasonw@ariel.its.unimelb.edu.au
Document: W2
Item Number: Appendix A: Glossary
Part of Item: 
Comment Type: technical
Comment (Including rationale for any proposed change):
In the definition of \"Web page\" the phrase \"is not embedded in another

resource\" needs to be clarified.

Consider for example an image, which (as is typically the case) has its own

URI. It can be used in two ways: (1) by being embedded in, i.e., rendered

together with, another resource. In this case it is not a Web page. (2) It can

be linked to, or returned as the result of a user interface action, without

being embedded in anything else. In this case it is a Web page by definition.

What determines whether it counts as a Web page or not is how it is used.

The ambiguity lies in the failure to specify what should be taken into account

in ascertaining how a resource is used for the purpose of applying the

definition. This has conformance-related consequences. Suppose for example

that, on your Web site, a particular image is embedded in an XHTML document

(using the IMG element or the SRC attribute of XHTML 2.0). For purposes of

your conformance claim, it is embedded in another resource, and hence not a

Web page. Assume further that on my Web site, the same image (at the same URI)

is referenced, but only as a link, and is therefore not embedded in another


If we interpret the \"not embedded in another resource\" requirement as meaning

\"not embedded in another resource anywhere on the Web\" then for purposes of

the conformance claim covering my Web site, the image is not a distinct \"Web

page\". However, if we interpret \"not embedded in another resource\" as applying

only to a \"set of Web pages\" as defined in WCAG 2.0, then it appears that the

image is a Web page for purposes of my conformance claim (because it\'s never

embeded in any of my content), but is not a Web page for purposes of your

conformance claim (as it is embedded in one of your other resources). Under

this interpretation, it appears that my Web site will have conformance

difficulties, if the image format does not support the inclusion of text

alternatives, titles, etc., and the image thus cannot conform to WCAG 2.0 as

an independent entity. The same problem arises if the image format does

support text alternatives but you haven\'t supplied one in the image itself,

whereas (let\'s assume) you have supplied one as part of the page in which the

image is embedded. In both cases, the image is a \"Web page\" for purposes of my

content, but not for purposes of yours, and my Web site as a whole doesn\'t

conform to WCAG 2.0.

However, if WCAG were to adopt the first interpretation mentioned above,

whereby a resource is \"not embedded in another resource\" only when it is not

so embedded anywhere whatsoever, then it appears that the conformance attained

by my Web site, given the above scenario, now depends on whether anybody

else\'s Web site embeds the image in another resource. Hence, the conformance

of my site depends on other peoples\' actions, totally unrelated to my content,

and this doesn\'t seem satisfactory either.

Proposed Change:
I haven\'t thought of a good solution, since as shown above, both of the

obvious answers have problems.

Moreover, the kind of scenario that results in this difficulty could actually

occur in practice: all that needs to happen for example is for one Web site to

link directly to an image (or other embeddable resource) on another site,

instead of linking to the page of the other site in which it is embedded.
Received on Wednesday, 23 May 2007 05:36:36 UTC

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