I'm new to the whole WPS/PQR landscape, so forgive me if I'm asking something obvious.  I'm preparing a WPS for a D17-1 spec using 17-7 PH.  I've been reading through D17.1 and B2.1, and I'm not finding an M number for 17-7 PH (or 17-4 for that matter).  If I can't find the base metal in AWS's 200-page crazy table of base metals, should I go with the ASME or UNS number?  B2.1 doesn't really say anything about how to address metals not included in their list of base metals or filler metals, and D17-1 just refers to B2.1 for how to structure the WPS.  Any help would be appreciated.

Thanks,
-Amy