Sketch of entry to a system action

When the existing system is entered in response to a user call, the basic information presented to the system is a pointer to an input parameter list (IP list), in the user's address space. This list contains information which defines the objects involved in the action, including the operation itself as the first object. There are two means of defining an object, direct and indirect. A direct definition consists of an index in the local C-list of a capability for the object. An indirect definition consists of an index in the local C-list of a capability for another C-list, and an index in that other C-list of a capability for the desired object.