What version numbering scheme to use?

Question

I\'m looking for a version numbering scheme that expresses the extent of change, especially compatiblity.

Apache APR, for example, use the well known version number

Answer 1

Purely for completeness, i will mention the old Apple standard for version numbers. This looks like major version. minor version. bug version. stage. non-release revision. Stage is a code drawn from the set d (development), a (alpha), b (beta), or fc (final customer ship - more or less the same as release candidate, i think).

The stage and non-release revision are only used for versions short of proper releases.

So, the first version of something might be 1.0.0. You might have released a bugfix as 1.0.1, a new version (with more features) as 1.1, and a rewrite or major upgrade as 2.0. If you then wanted to work towards 2.0.1, you might start with 2.0.1d1, 2.0.1d2, on to 2.0.1d153 or whatever it took you, then send out 2.0.1a1 to QA, and after they approved 2.0.1a37, send 2.0.1b1 to some willing punters, then after 2.0.1b9 survived a week in the field, burn 2.0.1fc1 and start getting signoffs. When 2.0.1fc17 got enough, it would become 2.0.1, and there would be much rejoicing.

This format was standardised enough that there was a packed binary format for it, and helper routines in the libraries for doing comparisons.