There is a set of programs called the Terminal Support System that can be used to customize the interface between an application {or development environment} and its terminal{s}. It consists of several modules that handle echoing, code translation, and other functions.

Programs currently supported are those that assume the terminal is one of the following "virtual terminal types":

At present the following real terminals are supported:

Any program can be connected to any terminal, except that currently programs using the 3270 virtual terminal cannot be connected to asynchronous Ascii terminals.