Defining subroutines

Define subroutines to allow chunks of code to be reused from different parts of the main program. Subroutines are called by the CALL SUB command.

You define subroutines by using the SUBROUTINE statement, which must be coded at the end of the program stream from which they are being called. SUBROUTINE statements must not be contained within INCLUDE statements, but subroutines can contain INCLUDE statements.

A subroutine must start with SUBROUTINE and end with RETURN, but a RETURN statement is assumed when the next SUBROUTINE statement or the end of the stream of code is encountered. You can use IF-THEN-ELSE to issue a RETURN statement to conditionally exit a subroutine.