access lists

[utzoo!decvax!ucbvax!unix-wizards]

>From dee at CCA-UNIX Wed Oct 21 10:58:15 1981
I believe that MULTICS goes even further and allows an arbitrary process
to be started to determine if a user can access a file.  Thus you could
have a user's access be determined by the time of day, system load,
phase of the moon, or whatever.  This also gives you the capability of
logging the access however you want to.  Needless to say, there is overhead
associated with all of this.

If you want to generalize things a bit and allow files to have access lists
whose elements can be either user or group IDs, you can get many fine
gradations of security and the almost always directly correclated inconvenience.