Every score has versioning information at the bottom of both the cover page and the title page. Rather than employing traditional opus numbers, I use a scheme that indicates the composition number (roughly in the order in which things were written), a version number to distinguish between modified editions, and an indicator as to the version of Finale in which the score is written.

V0101-003-F2014

This would be composition number 101, version 3, written in Finale version 2014.

Generally, version numbers indicate minor changes. A score which has undergone major modification would also include text such as revised edition on the title page itself.

Parts and reductions include an indication at the end of the composition number as to the instrumentation.

V0101PV-001-F2014 is a piano-vocal score
V0101FL-001-F2014 is a flute part