V2 Specification Browser
Browse HL7 v2 versions 2.1 through 2.9
The HL7 v2 specification across 14 versions, from 38 segments in v2.1 to 194 in v2.9, fully cross-referenced.
What You Can Browse
Every field of the PID segment in v2.5.1, with its data type, optionality, length, and table binding.
Segments
Segment definitions for every version (from 38 in v2.1 up to 194 in v2.9) with field-level detail, data types, and table bindings
Data Types
Primitive and composite data types with component structure, lengths, and format rules
Tables
HL7-defined and user-defined coded value tables with codes, descriptions, and usage notes
Message Structures
Segment ordering and grouping rules for each message type (e.g., ADT_A01, ORM_O01)
Trigger Events
Message triggers with descriptions, associated message structures, and acknowledgment rules
Data Elements
Field-level definitions with data type, length, optionality, and table binding details
Message Types
ADT, ORM, ORU, MDM, and all other message type categories with supported events
Queries
QBP/RSP query patterns and response structures for data retrieval
ACK Choreography
Acknowledgment flow definitions for original mode, enhanced mode, and accept/application ACKs
Documentation
Original specification chapters rendered from the HL7 database with examples and conformance notes
Supported Versions
v2.1
1992. Earliest supported release
v2.2
1994. Added master files (MF*, OM*) and pharmacy (RX*) segments
v2.3
1997. Major expansion
v2.3.1
1999. Errata and clarifications
v2.4
2000. Added QBP/RSP queries with conformance statements
v2.5
2003. Enhanced data types
v2.5.1
2007. Meaningful Use baseline
v2.6
2007. Added claims/reimbursement and materials management chapters
v2.7
2011. Reworked field lengths (conformance lengths, truncation)
v2.7.1
2012. Errata and updates
v2.8
2014. Added CDA awareness
v2.8.1
2014. Minor refinements
v2.8.2
2015. Additional corrections
v2.9
2019. Latest published version
Cross-Version Search
Search across all 14 versions simultaneously to find segments, fields, or data types. Each result links directly to its definition and carries a version badge; when results span multiple versions a per-version hit-count strip is shown, and you can sort by version (newest or oldest first) to track how a segment or field evolved between releases.
Use the version selector in the toolbar to switch between versions. The URL updates automatically for bookmarking and sharing.