A collection of user group IDs. Unlike in GroupMask, users in these groups are excluded from this mask instead of included.
Add a group to this mask
The group to add
Add multiple groups to this mask
The groups to add
Remove all groups from this mask
Remove a group from this mask
The group to remove
Whether the group was removed from this mask
Check if a group is in this mask
The group to check
Whether the group is in this mask
Convert this from a mask containing everything but these groups to a mask containing only these groups.
Make this mask contain only the given groups
The items to add