With the `--branch` option, the command takes a name and checks if
it can be used as a valid branch name (e.g. when creating a new
-branch). The rule `git check-ref-format --branch $name` implements
+branch). But be cautious when using the
+previous checkout syntax that may refer to a detached HEAD state.
+The rule `git check-ref-format --branch $name` implements
may be stricter than what `git check-ref-format refs/heads/$name`
says (e.g. a dash may appear at the beginning of a ref component,
but it is explicitly forbidden at the beginning of a branch name).
When run with `--branch` option in a repository, the input is first
-expanded for the ``previous branch syntax''
-`@{-n}`. For example, `@{-1}` is a way to refer the last branch you
-were on. This option should be used by porcelains to accept this
-syntax anywhere a branch name is expected, so they can act as if you
-typed the branch name.
+expanded for the ``previous checkout syntax''
+`@{-n}`. For example, `@{-1}` is a way to refer the last thing that
+was checked out using "git checkout" operation. This option should be
+used by porcelains to accept this syntax anywhere a branch name is
+expected, so they can act as if you typed the branch name. As an
+exception note that, the ``previous checkout operation'' might result
+in a commit object name when the N-th last thing checked out was not
+a branch.
OPTIONS
-------
EXAMPLES
--------
-* Print the name of the previous branch:
+* Print the name of the previous thing checked out:
+
------------
$ git check-ref-format --branch @{-1}