Message type, one of following:
0001 = Purchase, Balance or Preauthorization (See field 21),
0005 = Purchase with authorization number,
0009 = Gratuity,
0011 = Credit note,
0013 = Cancellation/Capture,
0015 = Pre-paid (Mobile Recharge),
0017 = Abort ongoing transaction
0018 = External reader device restart command
0027 = Voucher/Coupon generation,
0029 = Card to Card transfer,
4544 = Kill application
9043 = Get terminal status,
9999 = Initiate CTLS tap event simulator,
2667 = Get connection status.
Length : 4
Type : Numeric