These sheets are the earlier 1936 Summer Olympics issues sold as blocks/souvenir sheets. Initial issue date was 1 August 1936.
Purchase price of the blocks was 1.20 M.
Those with “X” suffixes feature a normal swastika watermark — when viewed from the rear, the legs of the swastika point in a counterclockwise direction. The “Y” suffixes feature the rarer reversed swastika watermark, with the legs of the swastika pointed in a clockwise direction when viewed from the rear.