23.7.6.1 Switching between Branches
To switch between branches, type C-u C-x v v and specify the
version number you want to select. This version is then visited
unlocked (write-protected), so you can examine it before locking
it. Switching branches in this way is allowed only when the file is not
locked.
You can omit the minor version number, thus giving only the branch
number; this takes you to the head version on the chosen branch. If you
only type <RET>, Emacs goes to the highest version on the trunk.
After you have switched to any branch (including the main branch), you
stay on it for subsequent VC commands, until you explicitly select some
other branch.