symbolic notation:
HEAD::
- indicates the head of the current branch (i.e. the
- contents of `$GIT_DIR/HEAD`).
+ indicates the head of the current branch.
<tag>::
a valid tag 'name'
- (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
+ (i.e. a `refs/tags/<tag>` reference).
<head>::
a valid head 'name'
- (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
+ (i.e. a `refs/heads/<head>` reference).
For a more complete list of ways to spell object names, see
"SPECIFYING REVISIONS" section in linkgit:gitrevisions[7].