SELECT NOT OPTIONAL Statement

[klophockey]

I am trying to determine an problem I am running into while compiling a program with Fujitsu cobol that has been compiled with MF, ACU, RM and IS Cobol with no issues.

The code is
SELECT NOT OPTIONAL mast1-file ASSIGN TO "mast1"
ORGANIZATION IS INDEXED
ACCESS MODE IS DYNAMIC
RECORD KEY IS mast1-num
FILE STATUS IS mast1-status.

Fujitsu does not recognize the 'NOT OPTIONAL' in its compile. If I remove it from the Select statement, it compiles fine.

If found this:
The NOT OPTIONAL phrase has effect only when the file is opened input-output taken from

https://www.microfocus.com/documentation/visual-cobol/vc40pu5/EclUNIX/HRLHLHPDF209.html

What is the 'effect only when the file is opened as I-O'?? The mast1 file does get opened as I-O at some point in the program.....but what is the 'effect' that NOT OPTIONAL has on that operation?


Thanks very much for any input you may have.