# STIX versus XITS?

I hope nobody minds me asking, but why are there separate STIX and XITS math fonts, and how can I go about deciding which one I should use? Which one is best suited for which purpose? Is one of the two better than the other?

• STIX Math is the officially released font; XITS Math is the same, but with some table added that makes it in a better shape for unicode-math. – egreg Feb 8 '15 at 16:15
• work is underway to provide (la)tex support for the stix fonts as well as other "cleanup". the xits fonts were based on an early (beta) release of the stix fonts. when the stix fonts with tex support are finally released, i think they should be preferred, but there should be very little difference, really. – barbara beeton Feb 8 '15 at 16:46
• So, given @barbarabeeton's comment, XITS math is something of the past, given that it only has some (performance?) advantages when used with unicode-math, and future versions of (la)tex will make these obsolete, while improving support for STIX. I hope I've understood correctly. – John Sonderson Feb 8 '15 at 16:54
• XITS adds complete and well tested OpenType math layout support to STIX fonts (plus right-to-left math support) i.e. the stuff you need to have proper math layout in XeTeX and LuaTeX when using OpenType fonts. The current version of STIX fonts provide similar layout, but it is incomplete and have known bugs, work is underway to fix this in version 2 of STIX fonts (unreleased yet). – Khaled Hosny Feb 8 '15 at 19:07
• I look forward to the strengths of both STIX and XITS being brought together and merged into one STIX 2 package, with all their implemented functionality and features merged and bugfixes sorted out. So, would it be correct to say, that the current version of STIX has the fonts, but doesn't have math layout support, that is, no way to format something like $e^{\pi^(\abs{y\boxplus x})}$, whereas XITS OpenType math layout would somehow support this and redimension everything for you needed? – John Sonderson Feb 8 '15 at 19:45

For a bit of historical context, when the STI Pub released v1.0.0 of the STIX fonts it did not have any math layout support neither for TFM files for traditional TeX engines nor OpenType layout for modern TeX engines. XITS started as a community effort to provide OpenType layout support and make the STIX fonts usable with engines that support OpenType math layout (namely XeTeX, LuaTeX as well as Microsoft Office 2007 and later).

Later STI Pub released a version of STIX fonts with OpenType math layout, but it was incomplete and had known bugs, so XITS remains preferable if one wants to use unicode-math package.

A bit later, STIX support files for traditional TeX engines was released (the stix packages), but XITS does not provide equivalent support, so if one wants to use STIX fonts in a traditional LaTeX setup, the stix package is the only option (and it works in XeTeX and LuaTeX, too, but using the traditional font machinery of course).

STI Pub is working on next version of STIX fonts that should provide better OpenType math layout and revised glyph shapes (among other things), so it would supersede XITS in certain ways (XITS would still be useful for people who prefer the existing design, or want to do right-to-left math).

• I think it would be nice if right-to-left support were included in the future STIX fonts as well, I don't see any practical purpose of having two separate packages with none of them supporting both directions. – John Sonderson Feb 8 '15 at 20:19
• @JohnSonderson: That is up to STI Pub. – Khaled Hosny Feb 8 '15 at 22:32
• Just curious, if there's already a community effort then why don't STI Pub just directly incorporate the improvements, instead of making something on their own. – xji Feb 14 '15 at 4:07
• @JIXiang: you should ask them. – Khaled Hosny May 5 '16 at 0:49