Grand Master Key
Grand Master Key - Similar to a Master Keyed System but can be sub grouped to offer greater key control.
For example a Hotel would normally be on a Grand Master key.
The owner (or Manager) would have a Grand Master Key to open all the locks.
The Entertainment Manager would have a Sub Master Key to open the doors
that they are responsible for and the House Manager would have a sub Master key
for the Bedrooms. Neither can gain access to the others areas
but the owner (or Manager) can access all the doors.