In the OpenType 1.8 specification, this is called TupleVariation so let's be consistent with the spec. (The initial implementation in fonttools pre-dates OpenType 1.8).
This directory includes snippets that people might useful to get ideas from. The contents will come and go, don't rely on them being there or having a certain API. If you need it, copy it and modify it.
If you do and think your work is useful for others, please add a link to it here: