I have a few thoughts and these are purely speculation. Read my ramblings at your own risk because I don’t have much information to work with! It’s possible the facility code is used to segment groups instead of a facility. That would be very useful if you wanted to revoke the cards of a single group. Class of 2023 graduated, second shift laid off, only maintenance coming in.
Alternatively(or in addition) maybe their facility code numbers work like Linux permissions. For the sake of argument let’s say there are 3 buildings.
- Is no access
- Execute building
- Write Building
- Read Building
If you only have access to the Execute building you get FC1.
If you only have access to the Write building you have FC2.
If you have access to Execute and Wright buildings FC3. 1+2=3
If you have access to all buildings FC7. 1+2+4=7
Any combination creates a unique number that represents all of the buildings. Networking uses a similar system for calculating subnets.
If I were to apply this to Hex I believe the pattern would look like this
0, 1, 2, 4, 8, F
Then you could have up to 12 facility codes for 00-FF that represents any combination of access to 10 unique facilities or groups.