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Re: Error on generator-unable-to-provide-required-alt

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Mon, 2 Sep 2013 13:42:22 +0200
To: "Jan P." <proedie@arcor.de>
Cc: www-validator@w3.org
Message-ID: <20130902134222991420.c2dbf6ac@xn--mlform-iua.no>
Jan P., Thu, 29 Aug 2013 20:18:21 +0200:

> According to [1] 'A conformance checker must report the lack of an alt
> attribute as an error unless [...]: The img element has a
> (non-conforming) generator-unable-to-provide-required-alt attribute
> whose value is the empty string.'
> 
> However, when I feed the following HTML code to the validator, it
> reports two errors.

This is not a bug in the validator, first the spec says, about 
“guidance-for-conformance-checkers”: [1] 

”A conformance checker must report the lack of an alt attribute as an 
error unless one of the conditions listed below applies:”

Note that the “unless” does not imply that it ”must *not*” report it as 
error, when the conditions are fulfilled. This is also refleced in the 
specific advice:

“A conformance checker that is not reporting the lack of an alt 
attribute as an error must also not report the presence of the empty 
generator-unable-to-provide-required-alt attribute as an error. [ snip 
] Naturally, conformance checkers may report the lack of an alt 
attribute as an error even in the presence of the 
generator-unable-to-provide-required-alt attribute; [ snip ]”

Thus, if the validator *is* reporting lack of alt as an error, then 
there is no permission to accept the  
@generator-unable-to-provide-required-alt attribute. And if the 
@generator-unable-to-provide-required-alt attribute is present, 
validators ar still permitted to report lack of @alt as an error.

Hence, the validator behaves correctly.

[1] 
http://www.w3.org/html/wg/drafts/html/CR/embedded-content-0.html#guidance-for-conformance-checkers

-- 
leif halvard silli
Received on Monday, 2 September 2013 11:42:53 UTC

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