epubcheck
epubcheck copied to clipboard
w3c
epuchcheck reports under "info" that epub:type="backlink" is not recognized but "referrer" is no longer part of ESSV=
The Epub Structural Semantics Vocabuarly has undergone revision after the 1.0 release. The current ESSV version 1.1 no longer lists or accepts "epub:type="referrer" on a back link on a footnote. It is not deprecated but simply gone. It was dropped shortly after epub 3.0.1 was released if you look back of the history of ESSV docs.
When they removed "referrer" they added a draft "backlink" that nicely maps to the aria role="doc-backlink".
The new "backlink" has stayed as "draft" for literally years now.
If we add epub:type="referrer" on a footnote backlink we are technically violating the latest ESSV 1.1 spec.
If we add epub:type="backlink" on a footnote backlink, epubcheck in its INFO is listing it as unrecognized, but accepts then now long deleted "referrer".
Will you please modify epubcheck Info to accept epub:type="backlink" and remove the recognition of "epub:type="referrer" in order to meet the current ESSV recs?
Alternatively, since it is still draft perhaps allowing both epub:type="referrer" (even though no longer on the list - just for backwards compatibility) and epub:type="backlink" (even though still draft after many years). Or perhaps getting the ESSV to bring back "referrer"?
Unfortunately, Sigil is caught in the middle. If it autogenerates code to use the newer "backlink", epubcheck will say in its INFO setting that it is unrecognized. But if we use "referrer" we will be violating the ESSV 1.1 spec.
Note the following:
when you run EPUCheck with the optional -u/--usage parameter, it'll output the following message:
USAGE(OPF-088): C:/Users/user/Downloads/backlink.epub/OEBPS/Text/Section0001.xhtml(12,116): Unrecognized epub:type value "backlink".
In JSON mode, it'll be:
Code: "messages" : [ { "ID" : "OPF-088", "severity" : "USAGE", "message" : "Unrecognized epub:type value "backlink".", "additionalLocations" : 0, "locations" : [ { "url" : { "opaque" : false, "hierarchical" : true }
This gets mapped inside Sigil to an INFO warning.
This is related to this previous issue from 2016:
https://github.com/w3c/epubcheck/issues/713#issuecomment-260151527
Where you said epub:type attributes will no longer be checked but the correct form moving forward is "backlink" not "referrer"
So why is that OPF-088 "USAGE" message still being produced when backlink is used while it happily accepts "referrer"?
It is not deprecated but simply gone.
Right, referrer was never formally part of the structure vocabulary because it came out of the edupub work that ended up being abandoned.
referrer was also only ever a draft term, and was renamed to backlink exactly because we were doing DPUB-ARIA 1.0 and wanted the terms to line up (the web folks think of a referrer in a different way so asked us to change it). But because referrer was a draft and didn't have real status in the vocabulary, it ceased to exist once it was renamed even though you can still find referrer in the edupub spec because we'd stopped working on it by that point. Fun times.
The problem now is no one's taken ownership over deciding what to do with the draft terms so they just linger on in that status. I raised this problem a number of years ago now in https://github.com/w3c/epub-specs/issues/1019 but there was resistance to fully incorporating them and making it appear that the edupub work was being endorsed.
So, all that to say I don't know that we'll get any clarity from the working group on how to proceed here. What I can try doing is proposing that all the draft terms that match up with DPUB-ARIA roles be fully incorporated. Maybe that will be less controversial than adopting everything that the edupub folks created.
FWIW, the W3C document "EPUB Type to ARIA Role Authoring Guide 1.1, W3C Group Note" Dated 14 March 2023 clearly lists the epub:type backlink as mapping to the aria role "doc-backlink" with the set of allowable tags as "a" on or about page 9 in the pdf version with no mentions anyplace as it being "draft" at all.
So maybe the W3C did remove the "draft" at some point officially?
So maybe the W3C did remove the "draft" at some point officially?
No, when I wrote that guide in IDPF the drafts were all marked, but I think I took them off when we republished it in W3C as it's just a mapping guide and it cluttered the table -- I left it to the structure vocabulary to indicate their status since it's the official source.
So why is that OPF-088 "USAGE" message still being produced when backlink is used
that's an omission in the vocabulary maintained in EPUBCheck. This will be fixed in the upcoming maintenance release.
