%PARMS not always "trusted"?

[Dan <dan27649@xxxxxxxxx>]

I've got an FTP script running on Windows that calls an RPGLE program via
"quote rcmd Call RPGprog ...".  I need to know in the RPGLE program how many
parameters were passed because one version of the FTP script passes only
one, but another version passes five.  I was all set to use the %PARMS BIF,
but was unsure what to make of the following warning in the ILE RPG
Reference:

 The value returned by %PARMS is not available if the
 program or procedure that calls %PARMS does not pass
 a minimal operational descriptor. The ILE RPG compiler
 always passes one, but other languages do not. So if
 the caller is written in another ILE language, it will
 need to pass an operational descriptor on the call. If
 the operational descriptor is not passed, the value
 returned by %PARMS cannot be trusted.

What the heck is a "minimal operational descriptor"?  And does the caller in
this case (FTP script's "quote rcmd Call RPGprog ...") pass it?  If not, can
I specify it somehow?

TIA,
Dan