In versions of FIX prior to version 4.4, this message was known as the Allocation ACK message.
The status is indicated by the AllocStatus <87> field as follows:
For an Allocation Instruction Ack <P> message with AllocStatus <87> of "Accepted" in response to an Allocation Instruction <J> with AllocType <626> of "Calculated", it is recommended that the MatchStatus <573> field be used to denote whether any financial details provided in the "Calculated" Allocation Instruction <J> were matched by the Respondent. If a match takes place and succeeds, then the match status will be '0'(Compared and affirmed). If the match takes place and fails, or no match takes place, then the MatchStatus will be '1'(Uncompared or unaffirmed).