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Version numbering guideline

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The packJPG version consists of two parts the main version number and

the sub version string. An example: 'packJPG v2.4a', an older version of

packJPG, has the main version number '2.4' and the sub version string

'a'.

Compressed .pjg files are required to be compatible between subversions:

packJPG v2.4a compressed .pjg files can be extracted by packJPG v2.4,

packJPG v2.4b, packJPG v2.4c, ... and vice versa. Only if there is a

change in the main version number, encoded files can be incompatible

between each other: packJPG v2.4 won't extract packJPG v2.3 compressed

.pjg files and vice versa.

The subversion string is used to indicate smaller changes that won't

break compatibility, like, f.e., bug fixes or speed improvements. It can

also be empty (for the first new main version in a series) and should be

enumerated as 'a', 'b', 'c', ... , 'z', 'aa', 'ab', 'ac', ..., 'zz'. For

any highly specific improvements it might also be used differently, to

indicate these changes, f.e. 'packJPG v2.5fast'.

The main version number is changed directly in the source code via the

'pjgversion' (main version number) and the 'subversion' (subversion

string) constant variables.