HP 3000 Manuals

Accessing Files Programmer's Guide

Using Command Interpreter Variables and Expressions Within File 
Designators 

Your file reference may also contain command interpreter variables and
expressions that are evaluated before the file reference is parsed and
validated.  In the following file equation, the exclamation point (!)
instructs MPE/iX to substitute the variable name MYFILE with the actual
file designator assigned to that variable by the SETVAR command.

     SETVAR MYFILE,'FILE2.MYGROUP.MYACCT'
     FILE FILE1=!MYFILE

The HPFOPEN and FOPEN intrinsics also allow you to embed command
interpreter variables and expressions in the file reference.  The
following file references are valid when passed as formal designators:

     !MYFILE
     !MYFILE.!HPGROUP.!HPACCT
     !FILE1/![FINFO(-!FILE1",33)]

For more information about using command interpreter variables and
expressions, refer to the Command Interpreter Access and Variables 
Programmers' Guide (32650-90011).

MPE/iX 5.0 Documentation