Souvenir sheet "first central office stamp exhibition, Berlin", watermark XI, plate flaw IV "color point at the bottom in the U in exhibition", neat cancelled with event-related special cancel, photo expertize Paul BPP (2018) : "genuine and immaculate", Michel 450.- (in the cheapest watermark-variant - here however better variety - analogous to the souvenir sheet without plate flaw double = 900.-)