Any logical file number that has been created by the OPEN routine can be defined as an output channel. Of course, the device you intend opening a channel to must be an output device. Otherwise, an error will occur, and the routine will be aborted.

This routine must be called before any data is sent to any output device unless you want to use the screen as your output device. If screen output is desired, and there are no other output channels already defined, then calls to this routine, and to the OPEN routine are not needed.