OPPELN, 20 Pfg Prussian blue Numeral issue 1920, 10 Pfg on 20 Pfg blue overprint Type III a provisional issue 1920 as mixed franking on small item to Yonne (Auxerre) / France, double-circle OPPELN 14 3 20 * * f (OS handbook No. 237.19), single-circle arrival 28 3 20 YONNE, age and use marks typical of period