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New ITS Structures

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Notes to Readers

This is a work in progress draft, and far from complete


This will carry forwards in part from the XML ITS R1

Changes from Previous Release

This section documents the differences between this specification and XML ITS Structures R1

  • Schemas and UML Representations

This specification includes a definition of normative schemas and UML representations for the set of valid instances for a message.

  • The Use of Schema Processors - editorial change only

XML ITS R1 said "Schema processing is not a conformance requirement although this specification has been designed to make schema processing beneficial." This specification says "Schema processing is not a conformance requirement although this specification has been designed to support schema processing."

Prerequisites, Assumptions and Conventions

It is a prerequisite that readers have a general knowledge of XML technology. Readers unfamiliar with XML may gain the requisite knowledge from the following W3C standards:

It is assumed that the reader is familiar with HL7 version 3 terminology - especially those related to message definition (HL7 information model terminology, Message Instances, Message Types, Interactions, CMETs, wrappers, etc.). For more information on these, refer to the V3 Guide.

It is also assumed that the reader has a working understanding of UML (Unified Modelling Language).

Known Issues and Planned Changes

This could start quite big


Introduction and Scope

This document describes how HL7 V3 compliant messages can be expressed using XML. It describes how the definition of the set of valid XML instance documents is derived from a specific HL7 Message Type. It covers ISO levels 5 and 6. Those familiar with V2 might call these the "XML encoding rules" for HL7 Version 3 messages. It also defines a standard way to use W3C XML Schema and UML to describe these instances in a way that is human and machine readable.

Serialisation of HL7 Classes to XML

HL7 Class

HL7 Choice structures

HL7 attribute

HL7 model boundary

Reshaping of RIM based Models

Abstract Serialisation Model

Informal Extensions

Backwards and Forwards Compatability

The XML ITS R1 stated that "when there are different versions of either the abstract HL7 artifact definitions, or of the ITS, it is anticipated that these versions will be no more than a single XSLT transform apart." In this specification we hope to improve on that, maybe by using the mechamism described in the SPL (Structured Product Labling) specification.

The use of schema processors

Schema processing is not a conformance requirement although this specification has been designed to support schema processing. Where schemas are used receivers may use alternate schemas (including DTDs) than the ones provided by HL7.

Sending applications should not provide schema location hints for the HL7 namespace and receiving applications that perform schema processing should ignore such hints if provided and instead should use whatever other means they have at their disposal to locate the relevant official HL7 schemas or their own customizations thereof. It is in the interest of the receivers own security and safety not to use sender supplied schemaLocation hints.

Glossary entries

The entries here are words or phrases that are used inthis document and need to be defined in the Glossary.

  • Serialisation
  • Serialisation Model
  • Static Model
  • RIM based Model
  • UML
  • Model Boundary

Questions for Publishing

How do I do links to SPL?