Schema Validation
Structural validation against the HL7 v2 specification
Schema validation checks that your message conforms to the structural rules defined in the HL7 v2 specification for the selected version. This is the most fundamental layer of validation.
What Gets Checked
Data Types
Each field value is validated against its declared data type (ST, NM, DT, TS, CWE, etc.) including format and component structure
Field Lengths
Values are checked against minimum and maximum length constraints from the specification
Table Bindings
Coded fields bound to HL7 tables (e.g., Table 0001 for Sex) are checked for valid values
Optionality
Required fields (R) must be present. Conditional fields (C) are treated as optional at this layer; their conditions are only evaluated when a conformance profile with predicates is active (see Conformance Profiles)
Segment Structure
Segment names, field counts, and repetition are validated against the schema
Message Structure
Segment order and grouping are checked against the declared message type (e.g., ADT_A01). This check is opt-in via the "Validate message structure" toggle in validation settings, enabled by the Strict preset and off in Quiet/Medium because it can be noisy on partial or edited messages
Schema validation uses the version selected in the toolbar. Switching versions may reveal different issues since the specification evolves between releases.