Can someone explain how the column ug_grp_id is used? My current understanding of ug_main_grp_id and ug_uid is that the user ID specified in ug_uid is a member of the group specified in ug_main_grp_id. Is ug_grp_id used to assign members and rights of that group (ug_grp_id) to ug_main_grp_id?