Example of external filename assignment

 select fd-name
     assign to external envvar.

In this example, envvar must be an environment variable. Before executing the program, you must issue a SET (Windows) or export (UNIX) command to relate envvar to the physical filename you want to use:

set envvar=c:\test.dat
export envvar=/tmp/test.dat

At run-time, the filename fd-name is assigned to the file test.dat in the specified directory.