Data Types
HL7 V2 defines numerous data types:
Simple Data Types
- ST (String): Text data, up to 199 characters
- TX (Text): Text data, longer than ST
- FT (Formatted Text): Text with formatting
- NM (Numeric): Numeric values
- DT (Date): YYYYMMDD format
- TM (Time): HHMMSS format
- DTM (Date/Time): YYYYMMDDHHMMSS format
Complex Data Types
- CX (Extended Composite ID): Patient identifiers
- XPN (Extended Person Name): Person names
- XAD (Extended Address): Addresses
- XTN (Extended Telecommunication): Phone numbers
- CE (Coded Element): Coded values with text alternatives
Coding Systems
HL7 V2 supports various medical coding systems:
- LOINC: Laboratory observations
- SNOMED CT: Clinical terminology
- ICD-10: Diagnoses
- CPT: Procedures
- RxNorm: Medications
Message Events
Messages are triggered by events:
- ADT Events: Patient administration (A01-A62)
- ORM Events: Order messages (O01-O38)
- ORU Events: Observation results (R01-R32)
- SIU Events: Scheduling (S12-S26)
- DFT Events: Financial transactions (P03, P11)