What does the server-side code look like?
The AccuTerm GUI environment has a library of MultiValue BASIC subroutines that are installed on the server. The design-time software includes a code generator which produces source code a BASIC program that calls ATGUI subroutines to display the form, then drops into an event loop that detects the next event triggered by the client, then uses a large CASE statement construct to determine which control fired which event and transfers control to a user-written subroutine which handles the event, then simply executes a RETURN statement. The BASIC event handler gets or sets the values of controls on the form by calling other ATGUI subroutines.