Using representation clauses as an operating system interface

A set of Ada® packages and programs for performing system accounting under the Ultrix™ operating system on the VAX™ using VADS™ are described. These programs provide for the billing of timesharing customers based on amount of connect time and quantity of CPU usage. Interactions at the operating system level are accomplished through the use of representation specifications. A description of the changes required when the operating system data structures were modified by the operating system manufacturer during an upgrade are also presented.