ER: Unique ID for check-in

[erict]

Hi all. We would appreciate having a unique ID to reference to an atomic check-in for documentation purposes. I.e. we should be able to apply this ID afterwards to pull up all the files that were checked in at the time the ID was created. Eventually it would be awesome if we could then apply all the changes of that check-in to another branch (which I've learned from Perforce).
So Programmer X fixes some bug and checks in all the files for this fix. This creates an ID 12345 which can be documented as having fixed bug number 6789. If this bug also exists in a branch of an older version of the code, then Apply Merge# 12345 against that branch.

Thank you very much.
Eric T.