This is an inbuilt function function provided by PPWIZARD.
The purpose of this routine is to take a supplied absolute filename and convert it to a relative form where possible.
The return code is the original absolute full name or the relative one.
This routine takes at least one parameter as follows:
Other options are to use a "S" for use the relative filename only if its shorter than or equal in length to the long name, any other value means always use the relative version.