Font version and revision information


I'm in the process of updating some past typefaces with expanded character sets for more supported languages. In some cases I'm subtly revising a handful of characters and doing a general overview and update through this process, but nothing drastic.

How does one discern between 'Version' updates and 'Revision' updates.

It would seem what I'm doing would fall under a 'Revision', so I was wondering what the general consensus is that constitutes a 'Version' update?

Thanks for your feedback.