Maintain provides many different ways of controlling a procedure's flow of execution. You can:

• Nest a block of code. In commands in which you can nest another command—such as in an IF command—you can nest an entire block of commands in place of a single one by defining the block using the BEGIN command. BEGIN is described in BEGIN. in Command Reference
• Loop through a block of code a set number of times, while a condition remains true or until it becomes true, using the REPEAT command. REPEAT is described in REPEAT in Command Reference.
• Branch unconditionally to a block of code called a Maintain function ("Maintain functions" are often referred to more briefly as functions, and are also known as cases). You define the function using the CASE command, and can invoke it in a variety of ways. When the function terminates, it returns control to the command following the function invocation. The CASE command is described in CASE in Command Reference.

  Alternatively, you can branch to a function, but not return upon termination, by invoking the function using the GOTO command. GOTO is described in GOTO in Command Reference.

• Branch conditionally using the IF command. If the expression you specify in the IF command is true, the command executes a PERFORM or GOTO command nested in the THEN phrase, which branches to a function. IF is described in IF in Command Reference.

  Alternatively, you can nest a different command, such as a BEGIN command defining a block of code, to be conditionally executed by the IF command.

• Trigger a function or system action in response to a user event. When a user performs the event in a Winform at run time, the event triggers the function or system action that you have specified. Event-driven processing is described in Winforms and Event-driven Processing.