Please read the following details:
Call Screen XXXX : This statement is used to call the screen number specified in the statement. For e.g. If you execute the statement call screen 0100, it will call screen 100.
Leave to screen 0 : Take the Follwing example:
For every screen there is the next screen to be specified.
Screen Next Screen
When you are on screen 100 and the Leave to screen 0 statement is executed, then you exit from the application/program.
When you alter the sequence of the next screen by Statement say call screen 300 from screen 100, and then the Leave to screen 0 statement is executed you will return to screen 100.
Set Screen xxxx: This statement is used to alter the sequence of the flow temporarily. This statement will overwrite the Next screen field of the current screen with the one you want. After all statements in that module are executed, the set screen is called.
Leave Screen: This statement is generally used after Set Screen Statement. As this statement is executed, the control is transferred to the Set Screen. The processing staements after this statements in a module are not executed.