SYSGROUP system table

CREATE TABLE SYS.SYSGROUP (
	group_id	 UNSIGNED INT NOT NULL,
	group_member	 UNSIGNED INT NOT NULL,
	PRIMARY KEY ( group_id, group_member ),
	FOREIGN KEY group_id ( group_id ) REFERENCES
	SYS.SYSUSERPERM ( user_id ),
	FOREIGN KEY group_member ( group_member )
	REFERENCES SYS.SYSUSERPERM ( user_id )
)

There is one row in SYSGROUP for every member of every group. This table describes a many-to-many relationship between groups and members. A group may have many members and a user may be a member of many groups.