Type: Length
Message length, in bytes, forward to the CheckSum (10) field. ALWAYS SECOND FIELD IN MESSAGE. (Always unencrypted)
Added in protocol FIX.2.7
See in: FIX.4.0, FIX.4.1, FIX.4.2, FIX.4.3, FIX.5.0, FIX.5.0SP1, FIX.5.0SP2, FIX.5.0SP2 EP240, FIXT.1.1.