if victor caratini spends less than 20 days on optional assignment, he does not burn his option, and he's credited with a full season of major league service time and pay. also, any player who is optioned to the minor leagues after the third day following labor day shall receive major league service (but not major league salary) for the duration of his optional assignment.
the former is a clever way to keep hiura's bat in the lineup for 20 days and not spite victor caratini too much.