With fontspec, and XeTeX or LuaTeX it's possible to access a font's OpenType features, including the Style Sets, e.g. like this:


TeX.sx has already taught me how to find out which features are available. Assuming I don't have proper documentation of my font at hand, is there a way to find out which glyphs (in which contexts) will actually come out differently when I use a certain style set (or another OpenType feature)? It also seems to depend on the script and font family (e.g. small caps). I feel like LuaTeX would be able to do this.

A nice font with lots of features to test this is Junicode. For this specific case, however, all the features are neatly described in Specimens and User's Guide.

1 Answer 1


There’s DTL OTMaster, which can be used for free for inspecting a font (and for a fee, for font editing, too). It takes a little time to find out all the functions in the program, but e.g. the alternate glyphs available in a font can be found out by selecting Tools > 'GPOS'/'GSUB' Table Viewer and then 'GSUB' table from the first dropdown (Layout Table), then selecting different options in the Features menu. Then the Subtable view will show the glyphs affected by a feature, as a mapping table under “Report” and as a set of large-size glyphs under “Image”.

Ligature lookup: glyph image

Ligature lookup: mapping table

  • Wow, this is pretty much what I've been looking for! It'll probably take me some time to find out how the rules work, e.g. for deciding if the 'Q' with the shorter tail or the one with the longer tail should be used. The only reason I'm waiting a little bit with accepting your answer is that I'm still hoping for a LuaTeX solution.
    – doncherry
    Oct 8, 2012 at 17:01
  • Can this be done with FontForge? Nov 14, 2012 at 11:05
  • @martin-schroder Yes it can! Dec 11, 2012 at 16:53

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