ADT/ACK - Merge person - patient ID (for backward compatibility only)

An A39 event is used to signal a merge of records for a person that was incorrectly filed under two different PID-2 - Patient IDs. The "incorrect source patient ID" identified in the MRG segment (MRG-4 - Prior Patient ID) is to be merged with the required "correct target patient ID" identified in the PID segment (PID-2 - Patient ID). The "incorrect source patient ID" would then logically never be referenced in future transactions. It is noted that some systems may still physically keep this "incorrect identifier" for audit trail purposes or other reasons associated with database index implementation requirements.