I work on a numbering system that is similar to software revisions. Every edit gets a new decimal (but not actually decimal, you know what I mean) and a new front digit means that its either a complete rebuild, or a substantial rebuild.
Draft Zero indicates the initial thought process, ideas bouncing around and (sometimes) committed to paper. (A lot of draft zeroes exist on the back of envelopes or flyers… or rather, probably no longer exist.)
Editing and Revision are always important.