Slide 18 of 27 - The OPENPORT() function is used to open an ARexx port for your script to receive messages with. It will fail if the specified port is already open, so you can check for the port name in the same way as libraries, using the 'P' or 'PORTS' list specifier with the SHOW() function. - In this case, we use an ELSE DO block to give appropriate messages to the user.