Defines message type ALWAYS THIRD FIELD IN MESSAGE. (Always unencrypted)
Note: A "U" as the first character in the MsgType (35) field (i.e. U, U2, etc) indicates that the message format is privately defined between the sender and receiver.
*** Note the use of lower case letters ***

Added in protocol FIX.2.7

See in: FIX.4.0, FIX.4.1, FIX.4.2, FIX.4.3, FIX.4.4, FIX.5.0, FIX.5.0SP1, FIX.5.0SP2, FIX.5.0SP2 EP240.