Ilya,

Normal release number practises

Main.Sub.Bug

Main number increases with big functional improvements/additions or dramatic code overhauls (when you have to re- test several important functional area's again) or availability on a new OS (like Windows 7)

Sub number increases with important internal architectural (when you should retest a complete new subfunction or compatibility fixes with operating systems) and function extension (adding a feature within a functional area)

Bug numbering increases only due to bug and other software compatibility fixes

Often it is used in this format

9.99.999

Regards Kees