Reverts a post to the previous edit version, if any exists.
Rollbacks are actions taken by editors to revert a post to any previous edit version available. This lever only appears when a post has been edited at least once. Otherwise, there is no revision to jump back to.
It is, in essence, a way to flashback a post. Not like when you're watching Sliding Doors, starring John Hannah, and they show you a point in the movie that their actions diverged from. That would be known as the rollback point and also a film starring a woman who is employed by Tony Stark and on a first name basis with Agent Coulson.
