I don't see much of that anymore. AFAIK, the recommendation is to use a float with 6 decimal places. You should highly consider your module for semantic versioning.

I never saw anyone mention "semantic versioning", and I think I know why, its absolute nonsense :) I can't tell if the idea has merit, its too hard to parse (compare to compare to http://www.json.org/ ).

All I can say is, whatever numbering scheme you adopt, make sure the documentation renders the number redundant information. Note important changes in the docs and in some kind of CHANGES file.