YYZ, Wherever XXX signifies the motion, YY indicates the case or product, and Z suggests the situation substance. Once again, letters may be added to the suffix to speak more specifics of the dial. In 1892 they introduced the earth to a minute-repeating watch—the 1st of its kind. In 1894, https://www.watchesworld.com/a-history-of-watch-reference-numbers/