The best known examples are for mainframe software, but IBM also used this same classification on smaller systems.
During the mainframe era, IBM made a wide variety of programs available to its customers.
These programs and their documents were distributed in the author's original form and were not subjected to any formal testing.
These libraries were maintained by the IBM Program Information Department, headquartered in Hawthorne, New York, with its distribution center in Mechanicsburg, Pennsylvania, which published separate catalogs for each compatible family of IBM Processors.
[2]Originally, these programs were not individually priced, but were provided at no cost as part of IBM’s service.