Allow application/x-font-ttf as a core media type for TTF fonts

I'm hoping someone can help me translate this error code into language I can understand and actionable steps. I formatted this epub using Atticus and uploaded with no problems to every vendor except D2D, who gave me this error message:
Errors
Amazon, Apple, Baker & Taylor, BorrowBox, D2D Print, Fable, Gardners, Hoopla, Kobo, OverDrive, Palace Marketplace, Smashwords, Tolino, Vivlio, and cloudLibrary will be disabled until this epub can pass EPUBCheck

INFO(CSS-007): /OEBPS/style.css(852,3): Font-face reference "https://8a1840b5-1962-4704-9ee2-12df2af50d1f.epubcheck.w3c.org/OEBPS/fonts/Spectral-Bold.ttf" refers to non-standard font type "application/x-font-ttf".

INFO(CSS-007): /OEBPS/style.css(860,3): Font-face reference "https://8a1840b5-1962-4704-9ee2-12df2af50d1f.epubcheck.w3c.org/OEBPS/fonts/Allura-Regular.ttf" refers to non-standard font type "application/x-font-ttf".

Many thanks for any light you can shed.

FYI, this isn't the best place to ask for help with validation errors. This is where the epubcheck application is developed so questions like this usually get closed because they aren't identifying bugs that need fixing. You're more likely to get help from the W3C publishing community group or in a mobileread forum.

That said, you need to change the manifest entries for the fonts in the package document so that their media types are "font/ttf" to make that info message go away.

EPUB allows any fonts, so it's not an error to use the old media type application/x-font-ttf but it's also not one of epub's core font media types (i.e., one that signals the font is guaranteed to be supported). I guess with the old media type they're assuming the font won't render, even though the media type is kind of meaningless in this case (the font will render because it is a supported format).

If you're not sure how to make the change manually, I'd suggest reporting the problem to the Atticus support folks to fix in their exports.

Thanks very much, Matt. I really appreciate your taking the time to explain this to me.

…

On Thu, May 22, 2025 at 4:35 PM Matt Garrish ***@***.***> wrote: *mattgarrish* left a comment (w3c/epubcheck#1612) <#1612 (comment)> FYI, this isn't the best place to ask for help with validation errors. This is where the epubcheck application is developed so questions like this usually get closed because they aren't identifying bugs that need fixing. You're more likely to get help from the W3C publishing community group <https://www.w3.org/community/publishingcg/> or in a mobileread forum <https://www.mobileread.com/forums/forumdisplay.php?f=179>. That said, you need to change the manifest entries for the fonts in the package document so that their media types are "font/ttf" to make that info message go away. EPUB allows any fonts, so it's not an error to use the old media type application/x-font-ttf but it's also not one of epub's core font media types <https://www.w3.org/TR/epub-33/#cmt-grp-font> (i.e., one that signals the font is guaranteed to be supported). I guess with the old media type they're assuming the font won't render, even though the media type is kind of meaningless in this case (the font will render because it is a supported format). If you're not sure how to make the change manually, I'd suggest reporting the problem to the Atticus support folks to fix in their exports. — Reply to this email directly, view it on GitHub <#1612 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BSY2OUHYF3REBR4YU27IXTT27ZNMZAVCNFSM6AAAAAB5XIXQW2VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDSMBSHA2TKNRXG4> . You are receiving this because you authored the thread.Message ID: ***@***.***>

-- Sadira Stone Cozy, funny, spicy, grownup romance http://sadirastone.com Visit Sadira on all the socials! <https://linktr.ee/SadiraStone>

Note that I reopened w3c/epub-specs#667 and we're going to be adding application/x-font-ttf to the list of core media types for TTF fonts in w3c/epub-specs#2726

It will eventually mean that this info message goes away, but it could be a couple of years before it makes it into epubcheck and vendor systems, so it won't help you out now.

I'm going to flag this for implementation as part of EPUB 3.4, though.

Thank you!

…

On Mon, May 26, 2025 at 5:28 AM Matt Garrish ***@***.***> wrote: *mattgarrish* left a comment (w3c/epubcheck#1612) <#1612 (comment)> Note that I reopened w3c/epub-specs#667 <w3c/epub-specs#667> and we're going to be adding application/x-font-ttf to the list of core media types for TTF fonts in w3c/epub-specs#2726 <w3c/epub-specs#2726> It will eventually mean that this info message goes away, but it could be a couple of years before it makes it into epubcheck and vendor systems, so it won't help you out now. I'm going to flag this for implementation as part of EPUB 3.4, though. — Reply to this email directly, view it on GitHub <#1612 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BSY2OUHSKJDSFRCZRMQ7CXT3AMCGDAVCNFSM6AAAAAB5XIXQW2VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDSMBZGU3TINBYGQ> . You are receiving this because you authored the thread.Message ID: ***@***.***>

-- Sadira Stone Cozy, funny, spicy, grownup romance http://sadirastone.com Visit Sadira on all the socials! <https://linktr.ee/SadiraStone>

feat: add 'application/x-font-ttf' to core media types

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Allow application/x-font-ttf as a core media type for TTF fonts #1612

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Allow application/x-font-ttf as a core media type for TTF fonts #1612

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mattgarrish commented on May 22, 2025

SadiraStone commented on May 22, 2025

mattgarrish commented on May 26, 2025

SadiraStone commented on May 26, 2025

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