Open System Services Programmer's Guide

Note 3
You must insert a placeholder comma (,) if you omit optional parameters, unless you omit them
from the end of the list. Omitted optional parameters contain default values, if they are defined.
Procedures That Return a Condition Code
Example 3 (page 41) calls the Guardian procedures FILE_OPEN_ and READX to open and read
data from a Guardian file, which is provided as an input parameter to the procedure. FILE_OPEN_
returns a return value in retcode, and READX returns a condition code in CC.
40 Overview of the OSS Programming Environment