| Segment | Description | Chapter |
|---|---|---|
| ACC | Accident segment | 6 |
| ADD | Addendum segment | 2 |
| AIG | Appointment information - general resource | 10 |
| AIL | Appointment information - location resource segment | 10 |
| AIP | Appointment information - personnel resource segment | 10 |
| AIS | Appointment information - service segment | 10 |
| AL1 | Patient allergy information segment | 3 |
| APR | Appointment preferences segment | 10 |
| ARQ | Appointment request segment | 10 |
| AUT | Authorization information segment | 11 |
| BHS | Batch header segment | 2 |
| BLG | Billing segment | 4 |
| BTS | Batch trailer segment | 2 |
| CDM | Charge description segment | 8 |
| CM0 | Clinical study master segment | 8 |
| CM1 | Clinical study phase master segment | 8 |
| CM2 | Clinical study schedule master segment | 8 |
| CSP | Clinical study phase segment | 7 |
| CSR | Clinical study registration segment | 7 |
| CSS | Clinical study data schedule segment | 7 |
| CTD | Contact data segment | 11 |
| CTI | Clinical trial information segment | 7 |
| DG1 | Diagnosis segment | 6 |
| DRG | Diagnosis related group segment | 6 |
| DSC | Continuation pointer segment | 2 |
| DSP | Display data segment | 2 |
| EQL | Embedded query language segment | 2 |
| ERQ | Event replay query segment | 2 |
| ERR | Error segment | 2 |
| EVN | Event type segment | 3 |
| FAC | Facility segment | 7 |
| FHS | File header segment | 2 |
| FT1 | Financial transaction segment | 6 |
| FTS | File trailer segment | 2 |
| GT1 | Guarantor segment | 6 |
| IN1 | Insurance segment | 6 |
| IN2 | Insurance additional information segment | 6 |
| IN3 | Insurance additional information - certification segment | 6 |
| LCC | Location charge code segment | 8 |
| LCH | Location characteristic segment | 8 |
| LDP | Location department segment | 8 |
| LOC | Location identification segment | 8 |
| LRL | Location relationship segment | 8 |
| MFA | Master file acknowledgment segment | 8 |
| MFE | Master file entry segment | 8 |
| MFI | Master file identification segment | 8 |
| MRG | Merge patient information segment | 3 |
| MSA | Message acknowledgment segment | 2 |
| MSH | Message header segment | 2 |
| NK1 | Next of kin / associated parties segment | 3 |
| NPU | Bed status update segment | 3 |
| NTE | Notes and comments segment | 2 |
| OBR | Observation request segment | 4 |
| OBX | Observation/result segment | 7 |
| ODS | Dietary orders, supplements, and preferences segment | 4 |
| ODT | Diet tray instructions segment | 4 |
| OM1 | General segment - fields that apply to most observations | 8 |
| OM2 | Numeric observation segment | 8 |
| OM3 | Categorical test/observation segment | 8 |
| OM4 | Observations that require specimens segment | 8 |
| OM5 | Observation batteries (sets) segment | 8 |
| OM6 | Observations that are calculated from other observations segment | 8 |
| ORC | Common order segment | 4 |
| PCR | Possible causal relationship segment | 7 |
| PD1 | Patient demographic segment | 3 |
| PDC | Product detail country segment | 7 |
| PEO | Product experience observation segment | 7 |
| PES | Product experience sender segment | 7 |
| PID | Patient identification segment | 3 |
| PR1 | Procedures segment | 6 |
| PRA | Practitioner detail segment | 8 |
| PRC | Pricing segment | 8 |
| PRD | Provider data segment | 11 |
| PSR | Product summary header segment | 7 |
| PV1 | Patient visit segment | 3 |
| PV2 | Patient visit - additional information segment | 3 |
| QAK | Query acknowledgment segment | 2 |
| QRD | Original-style query definition segment | 2 |
| QRF | Original-style query filter segment | 2 |
| RDF | Table row definition segment | 2 |
| RDT | Table row data segment | 2 |
| RF1 | Referral information segment | 11 |
| RQ1 | Requisition detail-1 segment | 4 |
| RQD | Requisition detail segment | 4 |
| RXA | Pharmacy/treatment administration segment | 4 |
| RXC | Pharmacy/treatment component order segment | 4 |
| RXD | Pharmacy/treatment dispense segment | 4 |
| RXE | Pharmacy/treatment encoded order segment | 4 |
| RXG | Pharmacy/treatment give segment | 4 |
| RXO | Pharmacy/treatment prescription order segment | 4 |
| RXR | Pharmacy/treatment route segment | 4 |
| SCH | Schedule activity information segment | 10 |
| STF | Staff identification segment | 8 |
| SPR | Stored procedure request definition segment | 2 |
| TXA | Document notification segment | 9 |
| UB1 | UB82 data segment | 6 |
| UB2 | UB92 data segment | 6 |
| URD | Results/update definition segment | 2 |
| URS | Unsolicited selection segment | 2 |
| VTQ | Virtual table query request segment | 2 |