Lol the comments. I went through Perforce and ClearCase too.
I try to forget ClearCase.
It haunts my nightmares.
When we were migrating to git, some of the more senior engineers came up with a workflow that was described as "the best implementation of ClearCase in git that I've ever seen". It was meant as a compliment.
There's some good links there that describe the trouble VSS caused.