-`<arg_spec>`::
- an `<arg_spec>` tells the option parser if the option has an argument
- (`=`), an optional one (`?` though its use is discouraged) or none
- (no `<arg_spec>` in that case).
+`<flags>`::
+ `<flags>` are of `*`, `=`, `?` or `!`.
+ * Use `=` if the option takes an argument.
+
+ * Use `?` to mean that the option is optional (though its use is discouraged).
+
+ * Use `*` to mean that this option should not be listed in the usage
+ generated for the `-h` argument. It's shown for `--help-all` as
+ documented in linkgit:gitcli[5].
+
+ * Use `!` to not make the corresponding negated long option available.