Two security features are built into the UserList stack: clearance and options. These two fields are placed in the global variables userClear and userOpt. They can then be used to make decisions about what parts of Hyper House a user has access to. (Initially, userClear is set to "low", and userOpt is set to empty.)
The intention is that the clearance is a level, whereas the options are a list of authorization options.
Option "readAny" allows a user to read any messages, even private ones. Option "killAny" allows a user to kill any messages, even private ones.