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Description
Hi,
the metadata 'a11y' prefix in OPF occurs an error.
e.g. <meta property="a11y:certifiedBy">
from EPUB Accessibility Vocabulary
Hi,
the metadata 'a11y' prefix in OPF occurs an error.
e.g. <meta property="a11y:certifiedBy">
from EPUB Accessibility Vocabulary
Activity
tofi86 commentedon Nov 24, 2017
Hi,
what exactly is the error message?
Did you declare the
a11y
namespace at the root element withxmlns:a11y="..."
?mattgarrish commentedon Nov 25, 2017
This is one of the needed updates for EPUB 3.1. It shouldn't have to be declared, although it's generally good practice to declare the prefixes.
As this is for a compact URI, the declaration needs to be done with the epub:prefix attribute:
tofi86 commentedon Nov 25, 2017
Thanks Matt, I'm adding the
epub-3.1
label.tofi86 commentedon Nov 25, 2017
@garconvacher EpubCheck currently does not support EPUB 3.1 as we unfortunately have a severe shortage of development capacity. EPUB 3.1 support will take some time... Stay tuned...
garconvacher commentedon Nov 28, 2017
Hi,
Sorry for my late answer.
I didn't see the a11y prefix is from the epub 3.1 specs.
Thanks for your replys.
rdeltour commentedon Nov 28, 2017
Actually the prefix is defined in the EPUB Publications Reserved Prefixes document, which is a "living document". The "a11y" prefix was added while the WG worked on EPUB 3.1, but by being added there it should retroactively be allowed and pre-declared in EPUB 3.0.1 too (@mattgarrish correct me if I'm wrong).
The explicit prefix declaration suggested by Matt is a good workaround until the prefix is properly recognized by EpubCheck.
mattgarrish commentedon Nov 28, 2017
Correct, it's not exclusive to 3.1. It's just one of the new things that we added during that revision that haven't yet been added to epubcheck.
murata2makoto commentedon Feb 1, 2018
I think that addition of reserved prefixes is a mistake in EPUB 3.0.1. In Extending and Versioning Languages: Terminology, there is a definition of forwards compatibility.
I heard that Apple does not support the added prefixes. I guess that they do not like this non-forwards compatible change.
mattgarrish commentedon Feb 1, 2018
Apple not accepting them because they use of an older version of epubcheck is not the same as their not being forwards compatible. The specification requires that reading systems ignore unknown prefixes, so unless the reading system is non-conforming, actual lack of awareness isn't a problem.
But didn't we state somewhere in 3.1 that the addition of reserved prefixes is a convenience that should not be relied upon? I clearly remember @iherman pointed out this from the RDFa primer:
Or was it something we talked about doing but never formalized? If not, it should go in 3.2.
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