Quote:
Originally Posted by KevinH
And as I explained back in 2025, and here earlier, if there are third party metadata values in widespread use (non-dc) that Sigil should support even though they are not epub3 spec, please someone make a list and reach a consensus and I will add support for those into Sigil.
|
I scanned about 65,000 EPUB files from several independent collections (commercial bookstores, personal libraries and archived collections).
Interestingly, the number of legacy name/content metadata names is actually quite small.
Most of them fall into just a few categories:
- editor / production metadata
- Calibre metadata
- accessibility metadata
- vendor-specific metadata
These are the results from Poland; the situation is likely similar in other countries.
Spoiler:
Details:
The most popular element of the legacy meta:
Code:
<meta name="generator" content="[Misc_texts]"/>
I see this just as often:
Code:
<meta name="Sigil version" content="[version]"/>
A separate section is the metadata from Calibre:
- calibre:series
- calibre:series_index
- calibre:timestamp
- calibre:title_sort
- calibre:rating
- calibre:author_link_map
- calibre:user_metadata:...
I also come across (theoretically non-compliant with EPUB3, likely inserted automatically) accessibility entries. After all, all of these entries have their equivalents in the meta property:
- schema:*
- a11y:*
- dcterms:conformsTo
Or something like this:
Code:
<meta content="Ten e-book jest zgodny z wymogami Europejskiego Aktu o Dostępności (EAA)." name="text" />
(Text in content: "This e-book complies with the requirements of the European Accessibility Act (EAA)")
Distributor:
Code:
<meta name="distributor" content="[Misc_texts]"/>
Also, when I buy a file at some bookstores, I see the following message:
Code:
<meta name="x-elibri-trans-id" content="[transaction_id]" />
Because the set appears to be relatively small and stable, I think this functionality would fit much better in a plugin than in Sigil's core.
For my personal use, I use a simple plugin; I can expand on this project a bit, and such legacy name/content meta will be easy to handle. The plugin is for EPUB3 only.