Digging The Meta Inwards Epub 3: Using The Meta Chemical Part To Extend Metadata Inwards Epub 3, 3.0.1, (Not 3.1) As Well As 3.2

One of the principal areas addressed inward recent changes to the EPUB spec is metadata, which is undeniably an of import area. So I'm taking an chance hither to aspect briefly but closely at the opportunities nosotros are afforded inside the content.opf file for enhancing the depth of our metadata.

We tin come across from the EPUB documentation that the chance exists to utilization ONIX to announce maybe the utilization of a DOI through the meta/refines/property trio (which sometimes becomes a four-piece through the identifying of a scheme, every bit it does here):

<metadata xmlns:dc="http://purl.org/dc/elements/1.1/">     <dc:identifier id="pub-id">urn:doi:10.1016/j.iheduc.2008.03.001</dc:identifier>     <meta refines="#pub-id" property="identifier-type" scheme="onix:codelist5">06</meta>     … </metadata>

Or to inform the utilization of an ISBN:

<metadata xmlns:dc="http://purl.org/dc/elements/1.1/">     …     <dc:identifier id="isbn-id">urn:isbn:9780101010101</dc:identifier>     <meta refines="#isbn-id" property="identifier-type" scheme="onix:codelist5">15</meta>          <dc:source id="src-id">urn:isbn:9780375704024</dc:source>     <meta refines="#src-id" property="identifier-type" scheme="onix:codelist5">15</meta>     … </metadata>

But truthful to the opened upwards nature of EPUB, nosotros powerfulness determine to use MARC on or thus occasions, for instance for the description of a role (author, editor, illustrator, etc.):

<metadata xmlns:dc="http://purl.org/dc/elements/1.1/">     …     <dc:creator id="creator">Haruki Murakami</dc:creator>     <meta refines="#creator" property="role" scheme="marc:relators" id="role">aut</meta>     … </metadata>

And going fifty-fifty further, a mix of XSD, ONIX, MARC too EPUB-specific values appears to move encouraged, a veritable pick too mix of markup languages:

Notice inward each representative the selection of belongings from the available metadata meta properties list.

Considering the programmers of reading systems

The resultant exists that if nosotros are going to cherry pick from dissimilar markup schemes too vocab, too thus the reading systems must move able to translate these schemes for the metadata to move of use. The query is tin they? In theory, yes. In practice, nobody seems besides sure enough how sophisticated the platforms are too how much of this materials gets used or is useful, specially when distributors, for example, prefer to have metadata external to the EPUB inward ONIX format or inward to a greater extent than primitive ways.

I would personally query the wisdom of allowing the mix too correspond of markup schemes too vocab, because of the complexity it adds for parsers too the chance for error. And, since at that topographic point is probable to move a express subset of these schemes used it powerfulness good move preferable to possess got a bespoke hit of EPUB vocab (which has been inward business office used anyway). This would avoid the sometimes puzzling decisions that are made because of adopting other standards. For example, the bulk of our metadata tin move contained inside Dublin Core tags, e.g. <dc:date>, too yet for the modification of the parcel nosotros must use <meta property="dcterms:modified"> which seems rather incongruous. This is because it fits the Dublin Core logic but non EPUB logic, the bulk of Dublin Core borrowed inward EPUB metadata are "elements" but "modified" is classified every bit a property. (This I would combat makes no feel inward the context of an EPUB's metadata.)

Changes inward EPUB3.1 -> EPUB3.2: The Brief Return too Subsequent Disappearance of the OPF Namespace

Programmers of reading systems must also move aware of what's on the horizon too, too it's worth beingness aware of changes that powerfulness occur to the hereafter iterations of EPUB too where missteps possess got been taken.

The meta tag too its refines attribute brand an interesting representative hither because refines is deprecated and meta is removed in EPUB 3.1, the electrical current recommended standard, inward favour of the opf namespace (which has been resurrected from EPUB 2). But fifty-fifty though EPUB 3.1 is the electrical current standard, you should definitely non update your workflow. Why? First, because the tools are currently non EPUB 3.1 ready, the github page for EpubCheck notably warns "There is currently a severe shortage of developers working on the tool ... barely plenty to conduct maintain critical põrnikas fixes, too non nearly plenty to undertake the necessary upgrades needed to proceed the tool relevant, such every bit developing back upwards for EPUB 3.1." Second, it has been written in "Why Specs Change: EPUB 3.2 too the Evolution of the Ebook Ecosystem" on the EPUBSecrets site that EPUB 3.2 is going to possess got rollbacks to EPUB three to address the lack of adoption (including reinstating meta too refines and re-obsoleting the utilization of the opf namespace) too that, if anything, the best matter to do straight off is to migrate to 3.0.1 instead of 3.1.

This is confirmed past times the W3Cs ain report:

EPUB 3.2 tin move considered every bit a successor to both EPUB 3.0.1 too EPUB 3.1. While reverting sure enough incompatible changes to EPUB 3.0.1 that EPUB 3.1 introduced, it also retains nigh of the residue of the revisions that were made to EPUB 3.1.
Since EPUB 3.1 did non have widespread adoption, the community grouping has decided to retain a listing of all changes made during the EPUB 3.1 revision that are all the same reflected inward EPUB 3.2. This determination was made to simplify comprehension of what has changed since EPUB 3.0.1 (i.e., readers do non possess got to review EPUB 3.1 earlier beingness able to determine how this novel version updates EPUB 3.0.1).

This is expert tidings for those who possess got stuck amongst EPUB three but I'd recommend y'all do nothing, non fifty-fifty motion to 3.0.1 (even though EpubCheck has verified EPUB 3.0 upwards against 3.0.1 since version 4.0.0) unless y'all are confident that everyone inward your chain of distribution tin conduct maintain the version y'all project design on adopting. Otherwise your operate powerfulness good move wasted. Move forwards cautiously too bear witness every bit widely every bit y'all can.

It's worth noting hither that I come across no advert of EPUB 3.0.1 inward Apple's documentation or FAQs for iBooks, for example. Maybe Apple intend it non worth mentioning too causes no issues, or maybe changes inward 3.0.1 are non supported yet. The changes themselves are, every bit the version numbering suggests, fairly minor, lifting restrictions on the number of dc:source too dc:type elements identified inward an EPUB's metadata, tightening the spine requirements to include all content, adding a new belongs-to-collection meta property, for describing serial too sets, etc., too deprecating oeb-page-head too oeb-page-foot. But, nigh of import of all, the version number y'all employ inside the <package> tag of your content.opf file should rest 3.0.

An EPUB that adheres to EPUB three should not interruption nether a reading organization that adopts 3.0.1 but tin the same move said for a reading organization that strictly enforces EPUB three when presented amongst an EPUB 3.0.1 that it has no means of knowing is whatever dissimilar from what it expects from an older EPUB 3? While iBooks too others brand no advert of 3.0.1, I'm non going to brand whatever assumptions. But the matter I am going to do is to proceed an oculus on EPUB 3.2, because at that topographic point are deprecations at that topographic point that deed every bit a alarm to non bother implementing novel things that y'all haven't got circular to yet: for example, epub:switch too epub:trigger.

Based on what appears to move happening inward EPUB 3.2, it would seem similar the people setting the EPUB standards are noticing the extraneous materials that but doesn't larn used too they are willing to prune when they intend it is necessary. I'm hoping that this appreciation goes farther too that EPUB becomes a criterion that becomes to a greater extent than efficient to employ, explore too experiment with, to the betoken where at that topographic point is greater innovation.

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