You had patches you'd float with "changelists" on top of enlistments. Each part large enough in thhe org (for example Excel or Word) gets a "branch" and it gets "forward integrated" and "reverse integrated" to the main "branch".
From your perspective the tool used to submit stuff (usubmit usually) you just push to the same branch as everyone else in your org and if your code breaks things it gets "backed out" by an automatic process.
Using git now is so much nicer.