serve involving "any continuous movement" (see Rule 3.3 Manner), beginning in one 3-foot drive service zone and continuing into the opposite 3-foot drive service zone, is a fault serve. See Rule 3.9(h) Illegal Drive Serve.
(a) The drive serve zones are not observed for cross-court drive serves, the hard-Z, soft-Z, lob or half-lob serves.
(b) The 3-foot line is part of the 3-foot zone and defines a plane that, if broken, is an infraction. (See Rule 3.9h)