You might have problems finding film for it old boy - I believe Agfa ceased production of 25cm AR film some time ago, and it's years since Kodak stopped making 9.5 inch Aerographic .... yes, I know, I'm struggling to get me coat on now ....
It's the one after S 12 ................... haven't a clue old boy, unless perhaps an extra Staffel - Staffel 13? Or maybe 'Sonder', as in Sonderaufklarungs staffel? Special Recce Staffel?