- From: Leif Halvard Silli <lhs@malform.no>
- Date: Sun, 16 Aug 2009 23:11:38 +0200
- To: Henri Sivonen <hsivonen@iki.fi>
- CC: Sam Ruby <rubys@intertwingly.net>, Steven Faulkner <faulkner.steve@gmail.com>, Ian Hickson <ian@hixie.ch>, HTMLWG WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>
Henri Sivonen On 09-08-16 18.03: > On Aug 16, 2009, at 17:51, Sam Ruby wrote: > Based on what I gather from comments praising Dreamweaver and > from my own reasoning, I think the advice at step #2 should be > that an authoring application in the situation where its user > doesn't supply a text alternative must not generate a text > alternative (especially not from the file name) and must not > generate markup that masks the existence of the image (empty > alt or role=presentation). Therefore, an image tag without an > alt attribute or a role attribute should be generated when the > user of the authoring application hasn't affirmatively provided > a text alternative or an assertion of presentationality. I agree that it should not insert role="presentation" by default. However, since we both agree with Consensus in that <img> without @role defaults to role="img", it could insert role="img". Lack of @role would not be signal of lack of role ... Tools do not need to ask "Do you want to insert an <img>?" They could offer choice between IMG@role=presentation and normal IMG. Tools should not bug users about lack of alternative text unless the <img> has a non-presentational role ... That <img> defaults to role="img" makes not sense for authoring unless the requirements for role="img" follows by. The real question here is the role and use of empty alt="". I agree with you that the tool should not automatically insert an empty alt. But we may not agree about why. A tool should not automatically assume that an IMG with empty alt="" is equal to a IMG with role="presentation", but ask the author for confirmation. > As a matter of language design, I think the absence of the alt > attribute is a sufficient syntactic signal of its absence. The disagreeable point is/has been whether lack of textual alternative has any meaning other than "<IMG> with an absent text alternative". Another disagreeable point is whether such a thing automatically should trigger an error message. > I think adding more syntax for affirming its absence (e.g. > noalt, missing, etc.) is unhelpful. Agree. We should treat lack of @alt and empty alt="" as semantically identical. The Consensus Documents goes in that direction when it states that it doesn't mater if an <IMG> with role="presentation" has an empty alt="" or no alt at all. But it goes slightly in the opposite direction when it recommends that validators should say that an <IMG> with an empty alt="" but not @role should automatically get a role="presentation". A tool might have its internal semantics where empty alt="" is equal to role="presentation". But a validator should not derive any role from the fact that @alt is either omitted or empty. It may /assume/ a role, perhaps ... I think it is important that we do not let @alt and @role eat into each others roles. It must be clear that @role comes first and @alt comes second. The @alt content depends on @role and not the opposite. Thus it is problematic if one may change the role to "presentational" by adding an empty alt="" attribute. Would we be able to change the role to "presentational" through the adding of an empty aria-labelledby="" attribute as well? >> * Having @alt "required" in HTML 4.01 raised public awareness >> of Web accessibility in general. > > Agreed, however, the requirement has also caused people to > write software that puts stuff specifically disapproved by ATAG > 2 into alt just to satisfy validators. Or may be those behavior problems are due to the lack of a <presentationalimage> element ... -- leif halvard silli
Received on Sunday, 16 August 2009 21:12:24 UTC