Sharp angle on rim outside. Fired red. Graffito beneath numerals, read as 5 choes, 3 kotylai, "possibly the jotting of some other vessel's capacity" (Lang). Very close, P 19587 A 18-19:1, but less carefully ... Ca. 470 B.C.
Red glaze stemmed dish and black glaze mug ... AMS Horizontal (normal)
Black stemmed dishes ... AMS Horizontal (normal)