Type: char

Unique identifier of IOI message.
(Prior to FIX 4.1 this field was of type int)

Added in protocol FIX.2.7

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