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 match status will be '1-Uncompared or unaffirmed'.