Add application/font-sfnt as a legal media type for .ttf and .otf files

[baldurbjarnason]

SFNT-based fonts share application/font-sfnt as a legal media type as per IANA assignment.

This applies to .ttf and .otf font files (but not .woff files which use application/font-woff).

Promoting the use of a standard media type is obviously a better—more long-term—solution than telling people to use a vendor-specific media type like application/vnd.ms-opentype.

Currently, epubcheck gives a warning when the legal media type is used but no warning when the vendor-specific media type is used. Ideally, this should be flipped around but, in the meantime, adding application/font-sfnt as a legal media type will do.

(And, yes, the spec should be updated to reflect this).

[rdeltour]

You're certainly right that standard media type are preferable, however I believe that EpubCheck should not be changed unless the list of Core Media Types from the spec is updated.

I suppose the right approach is to first create an issue in the EPUB spec issue tracker.

[baldurbjarnason]

I think letting the EPUB spec override standardised and specified practice that preexists it (the media types system) is a horrible precedent to set.

Is that seriously the consensus? (Follow the EPUB spec to a tee even when it's clearly out of date and contradicts other specs and practices.) If that's the case then I'll of course close the issue.

[rdeltour]

As far as I understand, EpubCheck’s goal is clearly to closely follow the spec, yes. That said, if something is obviously a bug in the spec or do not match reality, the usual approach is to issue a non-critical “warning" rather than a blocking “error”. Do you see a problem with that approach ?

I suggest we keep the issue open until a decision is made to amend the spec or not, as you filed in EPUB issue 443

[baldurbjarnason]

Nope. Sounds like a plan to me. :-)

[tofi86]

refs w3c/epub-specs#667

[tofi86]

refs w3c/epub-specs#443

[tofi86]

refs #586

[tofi86]

Resolved with EPUB 3.1 spec: https://idpf.github.io/epub-cmt/v3/#cmt-grp-content-documents
Setting the "3.1 label".

Core media types for fonts are now:

Media Type	Content Type Definition	Applies to
application/font-sfnt	[OpenType] [TrueType]	OpenType and TrueType fonts. Deprecate application/vnd.ms-opentype.
application/font-woff	[WOFF]	WOFF fonts

However, I have now idea how this behaves with backward compatibility.

[mattgarrish]

This is also related to #872. font/* media types were also added.

[rdeltour]

Fixed in #972.