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w3c / epubcheck

The conformance checker for EPUB publications
https://www.w3.org/publishing/epubcheck/
BSD 3-Clause "New" or "Revised" License
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Media overlay element ordering does not have to match content #1225

Closed mattgarrish closed 1 year ago

mattgarrish commented 3 years ago

The requirement for par and seq elements to match the default reading order has been moved to the accessibility specification. Epubcheck shouldn't emit errors now if there's a mismatch.

https://github.com/w3c/epub-specs/issues/1458

rdeltour commented 3 years ago

@murata2makoto said in #1244

I understand that this newly-added check ensures what has been required by the EPUB3 MO specification. This requirement is stated as "The ordering of these elements MUST match the default reading order of the EPUB Content Document." But there appear to be a number of Japanese DAISY publications that rely on some mismatch between the reading order and the occurrence order in MO documents.

We understand that some EPUB software such as the DAISY pipeline does not work when such mismatch occurs in an EPUB or DAISY publication. But Japanese DAISY people have used EPUB or DAISY readers that can live with this error.

This issue is quite similar to the mismatch between the navigation document and the spine document. We thus propose that such mismatch be treated as a warning rather than an error.

rdeltour commented 3 years ago

I think it's reasonable to preemptively demote MED_015 to a warning in the next maintenance release, if it happens before fully implementing EPUB 3.3.

rdeltour commented 3 years ago

EPUBCheck v4.2.6 now reports MED-015 as a USAGE. I'm keeping this issue open until we decide if we want to totally prune the feature and related code when we implement EPUB 3.3.

rdeltour commented 1 year ago

Closing this. MED-015 is still reported as a USAGE in v5.0.0. I think it may be helpful to some, so let's not remove that check entirely.