FPC's version numbering changed a few times over the years.
Versions before 0.99.5 are considered archaic. Their versioning was irregular.
After the release of 0.99.5 a system in version numbering was introduced, and that system was slightly updated after the 1.0 release.
Versioning for versions 0.99.5 - 1.0
- Compilers with an even last number are release versions (e.g. 0.99.8, 0.99.10, 0.99.12, 0.99.14 1.0.0)
- Compilers and packages with an odd last number are development versions (e.g. 0.99.9, 0.99.11, 0.99.13, 0.99.15)
- 0.99.5 is an exception to this rule, since 0.99.5 IS a release (a release prior to the introduction of this odd/even system).
- Letters behind the version number (0.99.12b, 0.99.5d) indicate release versions with some bugs and problems in the original release (respectively 0.99.12 and 0.99.5) fixed.
The main difference is that the difference between a release version is now in the second number (1.0.x vs 1.1.x) instead of the third number (0.99.14 vs 0.99.15), and the third number now becomes the patch level, replacing the postfixed letter in the old system.