Hi,

the fonts-libertinus package redundantly installs the font files in
both TTF and OTF formats, doubling the package size and likely
confusing services such as fontconfig. Please install the fonts only
in OTF format.

Thanks!

Cheers,

 - Fabian

The binary contents of the files is considerably different; they are not
merely (say) duplicate data with a different file extension. Different
glyph formats, obviously, but also different OTL features and different
hinting. Perhaps more, but seeing that, that's a sufficient set of
differentiation to conclude they're not interchangeable.

Folks can verify that with a basic:
ttx -l FONTNAME.ttf
ttx -l FONTNAME.otf

and go into more detail on a per-table basis as desired, also with ttx.

So they differ considerably in how they behave, and there may well be
target systems or downstream packages that reply on one where the other
would not do.

If the byte size is a concern for someone, they could perhaps make a case
instead that there should be separate packages for the build
variants/flavors (e.g., fonts-libertinus-tt and fonts-libertinus-cff) with
a metapackage that provides access to both, but that's probably a
maintainer's decision given all that would be involved.

Nate

Quoting Nathan Willis (2026-08-07 15:05:06)

More important than file size is whether the two formats use same font
identifiers, so that font systems like fontconfig cannot reliably
distinguish between them: If that is the case, then I believe they need
to either be packaged in separate binary packages that conflict with
each other, or installed *outside* of the normal font area and then
provide some mechanism at package install time to choose which set gets
symlinked into the font area.

 - Jonas

If you're referring to the patterns used by fc-match, there certainly
appears to be enough differentiation between the two build outputs to do
that. E.g., using the various `hint`/`hinting` keys.

Possibly also `fontformat`, but I rather suspect that in the real world
there's a lot of confusion lurking there (which is why I posited -tt- and
-cff- in the moot package names; steering clear of the file-extension at
least helps). At present, the files do seem to use different extensions, so
fc-match *could* currently lean on that, as-is; I just think it's not
recommendable as a way to identify font internals anymore, so finding other
keys is better.

Anyway, I certainly agree that detailed matching would be great; I just
also think that _also_ pushing more detail into the names of font packages
would be even more plusgreat.

OTOH, if you're just referring to the `name`-table entries, that's probably
doable, but I haven't checked those myself.

Nate

Quoting Nathan Willis (2026-08-07 16:10:43)

I am referring to the font name as identified by fontconfig.

 - Jonas