FOPEN returns a 0 if
the file could not be opened. Under
z/OS, files that have been opened
with FOPEN must be closed with FCLOSE at the end of a DATA step; files
are not closed automatically after processing.
FOPEN can be used to
open ddnames with instream data that are not already opened if you
specify 'S' for the open-mode attribute.
The default open mode
for the FOPEN function is I, which means input but also implies random
access. The I open mode is acceptable for a single-volume file because
the NOTE and POINT operations can be performed internally. However,
the operating system does not support NOTE and POINT across multiple
volumes in a file. If you use the I open-mode attribute to open an
external file that extends to multiple volumes, SAS flags it as an
error at OPEN time. The best way to get around this problem is to
specify S as the open-mode attribute to FOPEN. The S open-mode attribute
requests strictly sequential processing, and no conflict occurs.