All of the tools and languages in this guide are designed for use on character-based terminals. Therefore, they all make use of the Forms Runtime System (FRS) to display a graphical-looking form on non‑graphical, character‑based terminals.

FRS was originally designed for use in UNIX or VAX midrange environments with VT-style ASCII terminals. When you use FRS, an environment variable, term_ingres, defines the type of character-based terminal you are using and a termcap file provides the hardware-to-software mapping FRS uses to determine which key was pressed. The standard termcap file delivered with Ingres supports over 500 varieties of character‑based terminals and can be easily customized to support others.

If FRS applications are run on a graphical platform (like Microsoft Windows), they must run inside a character terminal emulation window.