perl-version

code working fine on Perl 5.12.1 doesn't work on 5.10.0

I wrote some code (about 100 lines) that is working fine on version 5.12.1. Unfortunately my client is using version 5.10.0. So I tested the code on 5.10.0 and found it doesn't work! Where can I find a list of differences between 5.10 and 5.12? Edit: I think the best answer to the question of "Where can I find a list of differences ...