If the version number is below 1, that's usually an indication that you are still in some alpha state.

Also, if the version string contains an underscore, this doesn't affect its numeric ordering, but CPAN.pm will not offer it as a "newer" version to replace an existing installed version. That way, you can tell testers that "version 1.42_03" is a development release, install at your own risk. Then eventually roll out 1.43 when you are happy.

-- Randal L. Schwartz, Perl hacker