4GL engine

The program that provides default functionality for a session to prevent application programmers from having to develop a session from scratch. The 4GL engine, formerly called standard program (STP), is used because essentially sessions are alike. In addition to providing default functionality, the 4GL engine also provides a mechanism to change the 4GL engine's default behavior, and to program dedicated functionality for a specific session. Each time a session is started, a separate 4GL engine instance is activated to handle the session.