Geoff Chappell - Software Analyst
This option names a filter program for the front-end C compiler.
The required argument consists of whatever follows immediately within the same command-line token, else is the whole of the next command-line token.
Whatever is named by pathname becomes a filter program for the C1 module. CL executes the named program instead of C1, but gives it a command line that starts with a pathname for C1 and continues with the command line that would otherwise have been given to C1.