The PMS level
This part presents the PMS structure dimension of the computer space. The sections are arranged in order of increasing organizational structure complexity. The sections are as follows; 1 Pc; 1 Pc with multiple Pio; multiprocessing with n Pc; parallel processing with n Pc; computers which are networks; and networks of computers.
In Chap. 37 Lehman defines the terms multiprogramming, multiprocessing, and parallel processing.