Looks like it is a result of US using Z for business.
Code:
SEASONALITY FROM UNITED STATES -
PERMITTED 22NOV14 THROUGH 28NOV14 FOR EACH
TRANSATLANTIC SECTOR. SEASON IS BASED ON TRIP DATE.
TO UNITED STATES -
PERMITTED 27NOV14 THROUGH 03DEC14 FOR EACH
TRANSATLANTIC SECTOR. SEASON IS BASED ON TRIP DATE.