Knowledge base


What is HL7® Version 3

HL7® version 3 is designed to be comprehensive in scope, complete in detail, extensible as requirements change, uptodate and modelbased, conformance testable and technology independent. It is based on the RIM (Reference Information Model).

There are two major standards developed by HL7 International: HL7® Messaging and HL7® Clinical Document Architecture™ (CDA™). Introduction of  version 3 of HL7® Messaging was the major change in strategy of HL7® standards development, focusing on semantic interoperability of all standards. HL7® v3 constitutes the family of standards (including HL7® CDA) based on common Reference Information Model (RIM) and XML as the implementation format for messages and documents.

The RIM was conceived as a universal reference model for healthcare interoperability, covering the entire health care domain. Each message specification would be a view into this model. The RIM is at the core of HL7® Version 3 and the version V3 cannot be understood without understanding the RIM. The effort to develop the RIM took place in two distinct phases. During the first phase, from about 1992 to 1999 a large complex class model with more was developed comprising more than a hundred classes and several hundred attributes and associations, supported by extensive documentation. In many ways this was just a rationalized super‐set of the content of HL7® V2. However, many people considered HL7® RIM model to be just too large to learn and use.