What is the name of this system?
I attend a small college in the U.S., and live on campus, and I was intrigued by the college's lock system. I wanna start off by noting that I must not mess, and am not interested in messing with, the locks or keys. The lock on "my" door is not really mine, and I could get in serious trouble with the state criminal system and the college's judicial process.
Okay, so there are a few dorm buildings on campus, and each building has around 6-10 suites, and each suite has 4 bedrooms. Each student can open the door for their building with their key, but they can't get into other dorms. Each student who lives in the dorm can open the door for their suite, but not for other suites. Each student in the suite can open their room, but not the other rooms in the suite. This is all done with each student having only one key.
I suspect the way this is done is that the first few pins are the same for everyone in the dorm, and the next few pins are the same for everyone in the suite, and the remaining pins are unique to the room. The dorm lock would only have pin stacks in a few chambers, the suite lock would have them in a few more, and the rooms would have complete pin stacks. It sound like this would be pretty common, at least for college dorms, but when I try to search for more information, I can't seem to find a name for the system. Is there a name? Is this common practice? How secure is this practice?
In case it matters, it appears the locks are all SFIC locks from MBS, with a couple from Best or Arrow. They are also mastered; a few people have keys that can open up every lock in a given dorm, and I suspect that there might also be a "higher" master that opens every lock in every building on campus.