Where to find the standard HL7v2 message schemas

The HL7v2 standard defines a set of message types, each with a specific structure. The structure of each message therefore follows an underlying model or schema (a formal description). When available in a structured format, these schemas can be used to validate the messages, generate code for parsing and serializing the messages, and perform other kinds of automated processing.

HL7 Abstract Message Syntax

The most "native" way to represent the HL7v2 message structure is by using the HL7 Abstract Message Syntax. This special notation is used in the normative HL7v2 documents and looks like this (example for the ACK^A01^ACK message type):

MSH
[{ SFT }]
[ UAC ]
MSA
[{ ERR }]

Official XML Schemas

In addition to the textual descriptions of the message types, HL7 provides a set of XML Schemas, which are suitable for automated processing. These XML Schemas can be downloaded from the HL7 website.

HL7 Database

The XML Schemas provided by HL7 are themselves based on the HL7 Database (HL7-DB), a structured representation of the HL7v2 specification. You can read more about the HL7 Database on Frank Oemig's website.

Other sources

There are also a number of other sources of the HL7v2 message schemas, including:

• HL7 Dictionary
• Schemas used by HL7 Tools for Visual Studio Code
• hapi-structures-vXX (generated using the proprietary HL7 database)