Terms outside Latin-1

Escaping is not what stops a Greek or Polish term from reaching your index. A PDF build has to be able to draw the characters, which takes an engine and a main font chosen for the job. Set both — the engine, and the font (which takes an options block, because it is named by file):

pdf-engine: xelatex
mainfont: STIXTwoText
mainfontoptions:
  - Extension=.otf
  - UprightFont=*-Regular
  - BoldFont=*-Bold
  - ItalicFont=*-Italic
  - BoldItalicFont=*-BoldItalic

xelatex is the engine, and STIX Two Text is the main font — named by file rather than by family, which is why the options above are needed. Naming it by file is what makes the build load the copy you installed: the family name STIX Two Text is findable too, but on a machine whose operating system ships a font of that name it finds that one instead, and the two are not the same build. STIX Two Text is not in a default TinyTeX install — it lives in TeX Live’s collection-fontsextra, so install it with tlmgr install stix2-otf. The general rule behind the recipe is that your main font must cover the script you are indexing; STIX Two Text is one font that does, not the only one.

Leave one of the two lines out and what you get depends on which — three paths in all:

  • Wrong engine. With pdf-engine: pdflatex the render stops and the LaTeX log says not set up for use with LaTeX, naming the character. A failed build is the friendliest of the three.
  • Wrong or missing font. With the right engine and a main font that does not cover the script, the render succeeds and the term is simply absent from the printed index. Nothing warns you.
  • No engine set. Quarto’s default engine is not pdflatex — on Quarto 1.10 it is lualatex — so leaving the pdf-engine: line out does not get you the failed build above. With the font set and the engine left alone, examples/unicode.qmd renders at exit 0 and its whole index prints correctly: on this Quarto the font is doing the work and the engine line is not what saves you. Set it anyway. It is the line that pins the behaviour to something this recipe states rather than to whichever engine your Quarto picks, and the failed build above is what you get if that default ever becomes pdflatex.

Do not read the log’s Missing character line as that missing-font failure. Under xelatex that line also appears for characters that print perfectly well: the engine draws a precomposed letter it lacks from the letter’s accent-plus-base spelling instead. The reliable check is the printed index itself.

sort= still works and still does only what it says — it sets one entry’s sort key. The order of the index as a whole is the index processor’s, and for non-ASCII terms it is best-effort; see Sorting an entry under something else.

This recipe is proven, with a typeset-print check in the test suite, for Greek, Cyrillic, and Latin beyond Latin-1 including terms written with combining marks — examples/unicode.qmd is the fixture. Any other script is unproven. In particular CJK and right-to-left scripts are not supported: STIX Two Text does not cover CJK, and RTL additionally has two problems no font fixes — the text is not shaped, and the comma between an entry and its page numbers lands on the wrong side of the entry.