https://www.python.org/dev/peps/pep-0426/#extras-optional-dependencies Gives an example of: "name": "ComfyChair", "extras": ["warmup", "c-accelerators"] "run_requires": [ { "requires": ["SoftCushions"], "extra": "warmup" } ] "build_requires": [ { "requires": ["cython"], "extra": "c-accelerators" } ] But I am not sure how to map the current setuptools example below to PEP-426: extras_require={ 'warmup': ['softcushions', 'barheater'], 'c-accelerators': ['cython', 'barheater'], } Would we expect multiple build_requires that list barheater, with separate extra lines, in PEP-426? Like so (adjusted to be all run-requires as extra setup-requires aren't a thing in setuptools today): "name": "ComfyChair", "extras": ["warmup", "c-accelerators"] "build_requires": [ { "requires": ["SoftCushions","barheater"], "extra": "warmup" } ] "build_requires": [ { "requires": ["cython", "barheater"], "extra": "c-accelerators" } ] Since build_requires is a key, I'm more than a little confused here. Seems like the extra has to be part of the key, or we're going to be uhm, stuck. -Rob -- Robert Collins Distinguished Technologist HP Converged Cloud