Comment 2 for bug 4662

I can't find even a summary of the different "foo:" revision spec namespaces anywhere in my bzr help -- I'd expect at least a pointer to this information from e.g. "bzr log --help" and "bzr diff --help", which are the main places I want to use -r.

I don't mind if all the details of revision specs aren't in the help for log and diff, but there should at least be a URL telling me where I can learn more. Features like "bzr diff -r ancestor:../parent" are very useful, but totally unadvertised at the moment.