Exchange/SNA Manual

AWAITIO Procedure
Exchange/SNA System Procedure Calls
104700 Tandem Computers Incorporated 5–5
You specify wait or nowait I/O in the call to OPEN that opens the subdevice (file) on
which you are performing I/O operations. Wait or nowait I/O is selected on the basis
of files. After you have opened a file and specified wait or nowait I/O, all subsequent
I/O operations on that file are wait or nowait I/O operations according to what you
specified when you opened the file. You cannot change the type of I/O operations to
be performed on a given file without closing that file and then opening that file again
with the new specification. For information on how to specify wait or nowait I/O, see
the OPEN procedure later in this section.