I've been using different variations of drawing number standards, depending on what company I'm designing for. Often folks will add a suffix to part numbers, e.g. 12345-01. The -01 can be the primary part, and the other variations of the same basic part can be -02, -03, etc. An example would be a molded case part that gets painted. -01 is the gray one, -02 is blue, -03 is pearl white, etc. One drawing can capture all these in tabular form (call it a "Tab Drawing" for short). In one company I worked for the drawing would be the -00, so it was obviously a drawing and not a physical part when listed in an assembly BOM. Yes, BOMs should include necessary documents, not just the physical parts.
Does anyone else have a version that is different than this one?