Message Structure
23 segments
R RequiredO Optional Choice
MSH
R1EVN
R1PID
R1PD1
O1MRG
O1NK1
O*PV1
R1PV2
O1DB1
O*DRG
O1OBX
O*AL1
O*DG1
O*DRG
O1PROCEDURE
O*PR1
R1ROL
O*GT1
O*INSURANCE
O*IN1
R1IN2
O1IN3
O1ACC
O1UB1
O1UB2
O12 events