Revision
A formally issued update to a document, carrying a new identifier (Rev A, Rev B) and a recorded reason for the change. Every revision supersedes the one before it — and the one before it must be visibly withdrawn, not merely replaced.
The mechanics are trivial; the discipline is not. A revision that is issued without the previous version being withdrawn from circulation leaves two documents claiming to be true, and the site will pick whichever one is nearest.
And the reason-for-issue matters as much as the number. A revision made for coordination is a different thing from a revision made because the design changed — the second is potentially a variation, and a project that does not record why a drawing was revised has lost the ability to tell them apart later.