. at-open-brace `@{` is used as a notation to access a reflog entry.
-With the `--branch` option, it expands 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.
+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). 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 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
-------
--normalize::
Normalize 'refname' by removing any leading slash (`/`)
characters and collapsing runs of adjacent slashes between
- name components into a single slash. Iff the normalized
+ name components into a single slash. If the normalized
refname is valid then print it to standard output and exit
- with a status of 0. (`--print` is a deprecated way to spell
- `--normalize`.)
+ with a status of 0, otherwise exit with a non-zero status.
+ (`--print` is a deprecated way to spell `--normalize`.)
EXAMPLES
--------
-* Print the name of the previous branch:
+* Print the name of the previous thing checked out:
+
------------
$ git check-ref-format --branch @{-1}
* Determine the reference name to use for a new branch:
+
------------
-$ ref=$(git check-ref-format --normalize "refs/heads/$newbranch") ||
-die "we do not like '$newbranch' as a branch name."
+$ ref=$(git check-ref-format --normalize "refs/heads/$newbranch")||
+{ echo "we do not like '$newbranch' as a branch name." >&2 ; exit 1 ; }
------------
GIT