The A37 event unlinks two PID segments previously linked with an A24 (link patient information) event.
ADT ADT Message Chapter
MSH Message Header 2
EVN Event Type 3
PID Patient (1) Identification 3
[PD1] Additional Demographics 3
[ PV1 ] Patient (1) Visit 3
PID Patient (2) Identification 3
[ PV1 ] Patient (2) Visit 3
[ { DB1 } ] Disability Information 3
ACK General Acknowledgment Chapter
MSH Message Header 2
MSA Message Acknowledgment 2
[ ERR ] Error 2