Protected subsystems have many applications, from
databases to common system management situations.
One use for a protected subsystem might be a group
membership list that you want to make available to all group members.
The list contains the names, addresses, personnel numbers, and interests
of group members. When the membership list is set up as a protected
subsystem, all members of the group can read selected information
and update specific types of information.
A protected subsystem might also solve the problem
of confidential information being sent to printers in public areas.
You could write an application to filter data for sensitive information.
Confidential files would be sent to printers in restricted areas,
while public files would be sent to any available printer. Any user
with execute access to the application could use the restricted printers,
but only through the protected subsystem.