UR_SYNCH_FRAME
case C(UR_SYNCH_FRAME, UT_WRITE_ENDPOINT):
case C(UR_SYNCH_FRAME, UT_WRITE_ENDPOINT):
case C(UR_SYNCH_FRAME, UT_WRITE_ENDPOINT):
case C(UR_SYNCH_FRAME, UT_WRITE_ENDPOINT):
case C(UR_SYNCH_FRAME, UT_WRITE_ENDPOINT):