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longdesc not working? #668

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jstallent opened this Issue Jan 11, 2016 · 9 comments

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@jstallent

jstallent commented Jan 11, 2016

I am working on an EPUB 3 file for BISG, and tried to use the longdesc property to describe an image. However, I'm getting the following error:

ERROR(RSC-005): ....EPUB/1-cover.xhtml(19,127): Error while parsing file 'attribute "longdesc" not allowed here; expected attribute "about", "accesskey", "aria-activedescendant", "aria-atomic", .....

The code in question is:

<section id="cover" epub:type="cover" role="main">
    <img id="coverimage" src="cover.jpg" alt="Cover page: Quick Start Guide to Accessible Publishing" longdesc="#coverlongdesc"/>
    <div id="coverlongdesc" class="hidden">January 2016. Compiled by the BISG Content Structure Committee&rsquo;s Accessible Publishing Working Group. Featuring: Creating accessible content, How accessibility adds value, Building teams &amp; processes, Legal requirements, Glossary, and more…</div>
</section>

I was under the impression that longdesc was supported in EPUB 3 documents. Am I wrong? Or am I doing something incorrectly?

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danielweck Jan 11, 2016

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I'm interested to hear more about the current status of longdesc in EPUB-Check as well. Spec.: https://www.w3.org/TR/html-longdesc/

That being said, your example naturally lends itself to aria-describedby, doesn't it? Spec.: https://www.w3.org/TR/wai-aria/states_and_properties#aria-describedby

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danielweck commented Jan 11, 2016

I'm interested to hear more about the current status of longdesc in EPUB-Check as well. Spec.: https://www.w3.org/TR/html-longdesc/

That being said, your example naturally lends itself to aria-describedby, doesn't it? Spec.: https://www.w3.org/TR/wai-aria/states_and_properties#aria-describedby

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mattgarrish Jan 11, 2016

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No, it's not supported as it's not in the core html 5.0 spec. It was resurrected as an extension, but for extension to be allowed they have to be listed in the extensions section of the content documents spec.

In code you posted, you could just switch longdesc for aria-describedby (and lose the hash, as describedby is a list if IDs.)

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mattgarrish commented Jan 11, 2016

No, it's not supported as it's not in the core html 5.0 spec. It was resurrected as an extension, but for extension to be allowed they have to be listed in the extensions section of the content documents spec.

In code you posted, you could just switch longdesc for aria-describedby (and lose the hash, as describedby is a list if IDs.)

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mattgarrish Jan 11, 2016

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I opened an issue a while back for 3.1 to be clearer about extensions:
w3c/publ-epub-revision#605

But it hasn't hit the radar yet.

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mattgarrish commented Jan 11, 2016

I opened an issue a while back for 3.1 to be clearer about extensions:
w3c/publ-epub-revision#605

But it hasn't hit the radar yet.

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jstallent Jan 11, 2016

Thanks, @mattgarrish. I was thinking that was the case.

@danielweck: The reason for using longdesc was just as an example (we expect people to rip open the EPUB and look at the code for examples of proper accessibility markup). I have aria-describedby in other places in the document, so I'll switch this one to that as well.

Thanks!

jstallent commented Jan 11, 2016

Thanks, @mattgarrish. I was thinking that was the case.

@danielweck: The reason for using longdesc was just as an example (we expect people to rip open the EPUB and look at the code for examples of proper accessibility markup). I have aria-describedby in other places in the document, so I'll switch this one to that as well.

Thanks!

@tofi86 tofi86 added the spec label May 16, 2016

@tofi86 tofi86 added the needs review label Jan 2, 2017

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tofi86 Jan 2, 2017

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The spec has been changed in the meantime. Needs to be reviewed again.

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tofi86 commented Jan 2, 2017

The spec has been changed in the meantime. Needs to be reviewed again.

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mattgarrish Jan 2, 2017

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Longdesc is still out. It was erroneously listed as an allowed attribute on the img element earlier on the HTML 5.1 revision, but was subsequently removed to avoid confusion that it remains an extension.

It is still not an allowed extension in EPUB 3.1. The following clarifying note was added to address extensions:

Note
Although [HTML] allows user agents to support vendor-neutral extensions, unless such extensions are listed in this section they are not supported features of EPUB 3.1.

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mattgarrish commented Jan 2, 2017

Longdesc is still out. It was erroneously listed as an allowed attribute on the img element earlier on the HTML 5.1 revision, but was subsequently removed to avoid confusion that it remains an extension.

It is still not an allowed extension in EPUB 3.1. The following clarifying note was added to address extensions:

Note
Although [HTML] allows user agents to support vendor-neutral extensions, unless such extensions are listed in this section they are not supported features of EPUB 3.1.

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tofi86 Jan 2, 2017

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Thanks for clarifying, Matt!

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tofi86 commented Jan 2, 2017

Thanks for clarifying, Matt!

@tofi86 tofi86 added postponed and removed needs review labels Jan 2, 2017

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StommePoes Jun 22, 2017

So, we're currently using hyperlinks to link to the long descriptions when the long descriptions themselves have structure, since aria-describedby expects to point to text (ie, pointing to a table as the long description of a chart or a graph is a total fail).
I take it we should continue using hyperlinks for our ePub3 long descriptions then?

StommePoes commented Jun 22, 2017

So, we're currently using hyperlinks to link to the long descriptions when the long descriptions themselves have structure, since aria-describedby expects to point to text (ie, pointing to a table as the long description of a chart or a graph is a total fail).
I take it we should continue using hyperlinks for our ePub3 long descriptions then?

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mattgarrish Jun 22, 2017

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At this time there isn't a way to provide structured access to a description beyond a mechanism like a hyperlink. The aria-details attribute is intended to address this problem, but it won't be available until ARIA 1.1 and HTML 5.2 become recommendations (5.2 makes its use in EPUB valid).

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mattgarrish commented Jun 22, 2017

At this time there isn't a way to provide structured access to a description beyond a mechanism like a hyperlink. The aria-details attribute is intended to address this problem, but it won't be available until ARIA 1.1 and HTML 5.2 become recommendations (5.2 makes its use in EPUB valid).

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