"U" for a good signature with unknown validity and "N" for no signature
- '%GS': show the name of the signer for a signed commit
- '%GK': show the key used to sign a signed commit
-- '%gD': reflog selector, e.g., `refs/stash@{1}`
-- '%gd': shortened reflog selector, e.g., `stash@{1}`
+- '%gD': reflog selector, e.g., `refs/stash@{1}` or
+ `refs/stash@{2 minutes ago`}; the format follows the rules described
+ for the `-g` option. The portion before the `@` is the refname as
+ given on the command line (so `git log -g refs/heads/master` would
+ yield `refs/heads/master@{0}`).
+- '%gd': shortened reflog selector; same as `%gD`, but the refname
+ portion is shortened for human readability (so `refs/heads/master`
+ becomes just `master`).
- '%gn': reflog identity name
- '%gN': reflog identity name (respecting .mailmap, see
linkgit:git-shortlog[1] or linkgit:git-blame[1])