It seems there is inconsistency in the naming of the Rip tool.
In the toolbar, it's called Rip Region and Rip Edge.
In the menu:
Additionally, there are a couple of things that seem confusing to me:
- Rip Region does not describe what the tool does precisely, as it rips vertices and edges only.
- Rip Edge does not rip edges, but vertices; technically you can rip an edge, but you don't want to ;)
- the name of the tool: "Rip Vertices", but the description says: "Rip polygons."
- there is no equivalent in the Edge menu, eg. "Rip Edge and Extend"
P.S. I've just discovered there is a UI Paper Cuts topic in the Forums, so if I should have posted this issue there, I apologize! ;)