Template:History of IBM mainframe operating systems/doc

Usage
This template is intended to be used on most of articles describing specific operating systems used on IBM mainframes. The main article is History of IBM mainframe operating systems. This template adheres to Summary style guideline.

Contents
Both IBM and non-IBM operating systems are included, the main criterium is a notable usage on IBM mainframe computers. This table cannot fit all the names, so choose only most important ones from each family.

The year in the table is a date of practical system introduction, whether in commercial, academic, or other environment.