What do (G) and (S) mean in samba's parameter configuration?

In the official documentation of [Samba](https://www.samba.org/) , the [smb.conf(5)](https://www.samba.org/samba/docs/current/man-html/smb.conf.5.html) page has an "Explanation Of Each Parameter" section. For some parameters, two possible values (either (G) or (S)) are shown at the end of the name, but nothing for others. What do (G) and (S) mean in samba's parameter configuration? (and _empty/nothing_?)