share has a GID in WGM - is it useable?

When looking at inherited groups for a full administrator, I saw entries for names that matched shares, with GIDs in the 400 range. Are these useful?

I'm trying to setup a user for a printer/scanner, that will have full access to a share on the server.

- can I/ should i assign this share (gid 40x) to the user? if so, how?