"merge" style, shows the original contents).
<branch>::
- Branch to checkout (when no paths are given); may be any object
- ID that resolves to a commit. Defaults to HEAD.
-+
-When this parameter names a non-branch (but still a valid commit object),
-your HEAD becomes 'detached'.
+ Branch to checkout; if it refers to a branch (i.e., a name that,
+ when prepended with "refs/heads/", is a valid ref), then that
+ branch is checked out. Otherwise, if it refers to a valid
+ commit, your HEAD becomes "detached" and you are no longer on
+ any branch (see below for details).
+
As a special case, the `"@\{-N\}"` syntax for the N-th last branch
checks out the branch (instead of detaching). You may also specify