Package Note to Readers

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Copyright Notice

This 2005 Health Level Seven V3 Publication is copyrighted by Health Level Seven, Inc. (HL7) and is therefore protected by the Copyright Law of the United States and copyright provisions of various international treaties. The effect of such laws and treaties is that you may not, without a license from Health Level Seven, Inc., copy or distribute HL7's publication Product. HL7 Organizational members are authorized to reproduce the publication for internal use in their organization. This authorization use does not include reproduction of any part of this publication for inclusion in products for direct commercial resale. HL7 Individual members may not reproduce any part of this publication.

HL7 Special Acknowledgments

In addition to acknowledging the Committee Co-chairs and Facilitators, special credit is due a number of contributors:

Special thanks go to George Beeler for serving as the V3 project leader and tools developer, Lloyd McKenzie with IBM for developing the Visio tool set for development of CMETs and Austin Kreisler with SAIC for development of the Publication Database. Helen Stevens is acknowledged for her leadership of the Publishing Committee. The following individuals are also acknowledged for their intellectual contributions: Wes Rishel with Gartner Group, Jim Case with University of California, Ken McCaslin with Quest Diagnostics, and Dale Nelson with Zed-Logic Informatics, LLC. The following individuals are acknowledged for their technical support in the production of this publication: Rikki Holland with Double Click, Ltd, Charlie McCay with Ramsey Systems, Ltd, Karen Van Hentenryck and Mike Craig with HL7, Matthew Stephens with Ramsey Systems, Ltd.

Contact Us

If you have questions regarding this publication you may contact the HL7 office at:

Health Level Seven, Inc. 3300 Washtenaw Avenue, Suite 227, Ann Arbor, MI 48104

734-677-7777 (phone) 734-677-6622 (fax) E-mail hq@HL7.org

2005 Version 3 Normative Edition Contents

Welcome to the 2005 Normative Edition of the Version 3 (V3) messaging standard. This package is the result of many years of work within the HL7 community and an increasingly focused effort with each new ballot cycle. We believe it is a major step forward for global health information standards.

The document you are currently reading is the Package Note to Readers document, which contains the following sections:

HL7 Organizational Overview

The HL7 Introduction section provides a brief overview of the HL7 Organization, its mission and philosophy.

HL7 Version 3 Overview

Review this section to understand what HL7 V3 is, why we developed HL7 V3, and the principles underlying the V3 Standard.

Getting Started

The V3 Publication is composed of two types of documents: Foundation and Domain. The Foundation documents are those documents that are broader in scope and tend to apply to all domain documents. THe V3 Guide, the HL7 Vocabulary Domain and Reference Information Model, for example, are Foundation documents. Domain documents are produced for a specific domain such as pharmacy or scheduling and contain the messages relevant to that domain.

Below is a graphical representation of the Foundation documents.

Version 3 Domains contain specifications for dealing with functional areas of healthcare. For example, Patient Administration, or Medical Redords.

Each Domain document has a common structure and contains a common set of artifacts.

Documents in the V3 2005 Normative Edition

The 2005 Normative Edition contains those Version 3 Standards that are ANSI Approved, those that have passed Membership Level Ballot and are awaiting final ANSI Approval, and Draft Standards for Trial Use (DSTU).

Foundation Documents

Foundation Documents are the basis for all of the other specifications. The RIM is the model on which all V3 Standards are based. Vocabulary defines terms and code sets. The Data Types Abstract Specification specifies the HL7 Version 3 Data Types on an abstract layer, independent of representation. Refinement, Constraints and Localization specifies what the HL7 Technical Committees are permitted to do as part of the Version 3 Refinement process. GELLO is intended to be a standard expression language for decision support.

• HL7 Reference Information Model (RIM)
• Data Types: Abstract Specification
• HL7 Vocabulary
• Refinement, Constraint and Localization
• GELLO: A Common Expression Language

Messaging Infrastructure

The Master File / Registry domain comprises the classes and attributes needed to support Master Files and Registries. The Message Control Act Infrastructure covers the alternate structures of the message Trigger Event Control Acts in the HL7 Composite Message. The Query Infrastructure domain specifies the formation of information queries and the responses to these queries. Transmission infrastructure describes the information model, messages and interactions related to the assembly of an HL7 v3 composite message.

• Master File/Registry Infrastructure
• Message Control Act Infrastructure
• Query Infrastructure
• Transmission Infrastructure

Transport Specifications

Transport Specifications detail how the messages are sent "over the wire."

• Transport Specification - ebXML
• Transport Specification: MLLP
• Web Services Profile

Implementation Technology Specifications (ITS)

The ITS:XML Datatypes specification defines standard representations for data values in XML. The ITS:XML Structures document describes how HL7 V3 compliant messages can be expressed using XML.This UML ITS implements the semantics of the Abstract Data Types specification using UML in such a way that HL7 data types are mapped into the core UML and OCL kernel data types where such mappings are appropriate.

• ITS:XML Datatypes
• ITS:XML Structures
• ITS:UML Data Types

Services

The HL7 Common Terminology Services (HL7 CTS) defines an Application Programming Interface (API) that can be used by HL7 Version 3 software when accessing terminological content.

• Common Terminology Services

Common Domains

CMETs (Common Message Element Types) are a work product produced by a particular committee for expressing a common, useful and reusable concept. Shared Messages are a work product produced for expressing common, useful and reusable message types.

• Common Message Element Types
• Shared Messages

Administrative Management Domains

Administrative Management Domains contain specifications that support Administrative Functions in healthcare facilities.

• Accounting and Billing
• Claims and Reimbursement
• Patient Administration
• Scheduling

Health and Clinical Management Domains

The Health and Clinical Managment Domains contain specifications from a variety of healthcare focus areas.

• Clinical Document Architecture
• Medical Records
• Public Health Reporting
• Regulated Studies

Reading the HL7 V3 Normative Edition Documents

The HL7 V3 Normative Edition is best viewed online due to the size of the document and the availability of extensive supporting materials. We are also making the entire package available on CD-ROM. You may also download the documents from the HL7 website.

What do the Colors on the Master Table of Contents Mean

If you look at menus that appear in the documents, you will notice that six colors are used. The colors indicate the type of document. The different types are enumerated below:

What do the Colored Symbols in the Documents Mean

Within the documents, you may find several icons that are designed or colored in such a way as to introduce the status of that particular item. Most commonly, main headings will have an icon for their ballot status. By hovering over the icons, you will find a descriptive term to better understand what this icon means. Here is a list of the ballot status icons used in these documents.

Ballot Status Icon Descriptions (link to graphic opens in a new window)

Ballot Status Icon Descriptions (continued) (link to graphic opens in a new window)

HL7 Organization Overview

Mission

HL7's mission is to provide standards for the exchange, management and integration of data that supports clinical patient care and the management, delivery and evaluation of healthcare services. Specifically, to create flexible, cost effective approaches, standards, guidelines, methodologies, and related services for interoperability between healthcare information systems.

What is HL7?

HL7 is one of several ANSI-accredited Standards Developing Organizations (SDOs) operating in the healthcare arena. Most SDOs produce standards (sometimes called specifications or protocols) for a particular healthcare domain such as clinical data, pharmacy, medical devices, imaging or insurance (claims processing) transactions. Health Level Seven's domain is clinical and administrative data.

HL7 is a not-for-profit volunteer organization. Its members - providers, vendors, payers, consultants, government groups, pharmaceutical and others who have an interest in the development and advancement of clinical and administrative standards for healthcare - develop the standards. Like all ANSI-accredited SDOs, HL7 adheres to a strict and well-defined set of operating procedures that ensure consensus, openness and balance of interest. A frequent misconception about HL7 (and presumably about the other SDOs) is that it develops software. In reality, Health Level Seven develops specifications, the most widely used being a messaging standard that enables disparate healthcare applications to exchange key sets of clinical and administrative data.

The HL7 Working Group is composed of volunteers who give their time on a personal basis or under sponsorship of their employers. Membership in the HL7 Working Group has been, and continues to be, open to anyone wishing to contribute to the development and refinement of the HL7 standards.

Background

The term "Level 7" refers to the highest level of the Open System Interconnection (OSI) model of the International Organization for Standardization (ISO). This is not to say that HL7 conforms to ISO defined elements of the OSI's seventh level. Also, HL7 does not specify a set of ISO approved specifications to occupy layers 1 to 6 under HL7's abstract message specifications. HL7 does, however, correspond to the conceptual definition of an application-to-application interface placed in the seventh layer of the OSI model.

In the OSI conceptual model, the functions of both communications software and hardware are separated into seven layers, or levels. The HL7 Messaging Standard is primarily focused on the issues that occur within the seventh, or application, level. These are the definitions of the data to be exchanged, the timing of the exchanges, and the communication of certain application-specific errors between the applications. However, of necessity, protocols that refer to the lower layers of the OSI model are sometimes mentioned to help implementers understand the context of the standard. They are also sometimes specified to assist implementers in establishing working HL7-based systems.

It does not try to assume a particular architecture with respect to the placement of data within applications but is designed to support a central patient care system as well as a more distributed environment where data resides in departmental systems. Instead, HL7 serves as a way for inherently disparate applications and data architectures operating in a heterogeneous system environment to communicate with each other.

If we consider the multitude of healthcare information systems applications as well as the variety of environments in which healthcare is delivered, it is evident that there are many more interfaces which could benefit from standardization. The interfaces chosen were considered to be of high priority by the members participating in the standards writing process. HL7's intent is to prepare a complete standard for these interfaces, built on a generic framework that is sufficiently robust to support many other interfaces.

HL7 Version 3 Overview

Why a Major New Version?

HL7 V3, like V2.x, is a standard for exchanging messages among information systems that implement healthcare applications. However, V3 strives to improve the V2 process and its outcomes. The original process for defining HL7 messages was established in 1987. It has served well since. However, as HL7 membership grew and its standards became more widely used, HL7 has become aware of opportunities to revolutionize healthcare interface computing. HL7 interfaces substantially reduce costs and implementation times when compared to the industry's experience with proprietary interfaces. However, these costs and times vary considerably by vendor, and the industry sees a need for improvement. Substantial optionality in HL7 makes it difficult to specify precise contract terms for HL7 interfaces. This can lead to unrealistic expectations that hurt vendors and buyers equally. The development principles behind HL7 V3 lead to a more robust, fully specified standard.

Difficulties with the Existing Process

The HL7 V2.x development process is entirely ad hoc. There is no explicit methodology. Members receive no formal guidance in constructing messages. Trigger events and data fields are described solely in natural language. The structural relationships among data fields are not clear. Segments are reused in many messages and message definitions are reused for many trigger events. In order to accommodate this extensive reuse, most data fields are optional. Chapters are inconsistent in their use of trigger events versus status codes. There is no specification as to when a specific kind of healthcare information system should be expected to honor a trigger event or accept a message.

With V2.x, a Technical Committee creates messages by editing word processing documents directly. The metadata is not available in a structured form until the staff and volunteers tediously extract it from the word processing documents after publication.

In summary, there is substantial need to improve this old process in order to handle the breadth and complexity of the challenges HL7 faces today. Our industry will benefit because this new process results in a more rigorous specification.

Opportunities to Improve

Fortunately, software practitioners have learned a lot since 1987. There are better methodologies. Computer support is far more available and cost-effective. However, HL7 cannot take advantage of these developments solely by minor tweaks to the old process.

HL7 spent four years characterizing its revised goals and creating a methodology to adapt modern analysis techniques from system building to message design. Initially the HL7 Board of Directors chartered an independent task force to establish the broad outline of the approach. In January 1996, the Technical Steering Committee (TSC) agreed to adopt the main features of the approach and take over its management. Planning work continued in the Modeling and Methodology Committee and the Control/Query Committee. At the completion of V2.3, in the spring of 1997, the HL7 Technical Committees all began to use the V3 process.

V3 Principles

The HL7 V3 standard development methodology is based on a set of principles providing a common philosophy for all HL7 V3 standard developers.

• Internationalization: V3 shall include mechanisms that support the need for local variants of HL7 messages to be used by HL7 Affiliates. It shall be possible for affiliates to use the messages created by the worldwide HL7 organization. It shall also be possible for affiliates to develop and use localized variants.
• Legacy Systems Support: As with prior versions, V3 shall be designed using a technological approach that permits implementation in "legacy systems." These are systems that have been implemented in technical environments that do not necessarily conform to or provide support for recent or pending "open systems" standards, such as those published by ISO, Open Systems Foundation, Object Management Group, etc. Similarly, HL7 will not require proprietary features of any operating system or software vendor. In practical terms, this means that V3 shall be able to exchange messages formatted in strings of printable characters, as is the case for all previous versions. This does not preclude HL7 from deciding to develop variants of its specification that make use of the modern technologies provided that 1) System builders will not be required to buy software from a sole source in order to implement V3, and 2) Messages generated in these formats have the same data content so that translation between the printable character format and other formats is easy.

• Loosely Coupled Systems: As with HL7 V2.x, V3 shall not be a standard for the functionality of the systems that exchange HL7 messages. However, where V3 includes a requirement to accept or send certain data or to send specific messages in response to trigger events or other messages, the application system may have to develop functionality to support those requirements.

  V3 messages may be sent using many modes and topologies. Messages may be sent in a manner that requires an immediate response, as unsolicited updates through a store and forward network, or in batches where the manner and timing of message transfer is not specified. V3 includes support for "one-to-many," store-and-forward distribution of messages by an external software agent.

• V2.x Functional Compatibility: HL7 V3 goals cannot be achieved while maintaining full compatibility with previous versions. However, upon completion, V3 shall cover the information content of the last version in the V2.x series including attributes and trigger events. This should not be construed to mean that all attributes and trigger events will be included in V3 in exactly the same form as within the V2.x series.

  A network that includes a mixture of systems that implement V2 and V3 will require message translation. Because the V2 standards have substantial optionality, the translations will use rules specific to the systems on that network. It is expected that interface engines and other translation software will be able to provide the translations between site-specific interpretations of V2.x and any implementation of V3.

• Upward Compatibility Among V3.x: HL7 will provide the maximum degree possible of interoperability among systems operating on older and newer versions of HL7 protocols in the V3 family through compatible enhancement.

  • A message structure that is modified in a newer version of the protocol must be acceptable to a system designed for the prior V3 release. However, a system built for the prior release will only extract the information that was defined for that prior release.
  • A message structure created in accordance with an older version of the V3 protocol must be acceptable to a system designed for a later V3 release. In some cases, this will mean that the system built for the newer release will not receive certain information fields because they were not a part of the older version of the message structure in use by a specific sender.
  • Where compatible enhancement is not possible, HL7 will require evolution in the protocol to happen gradually, so that users can introduce the change into their networks gradually.
  • The messages associated with all interactions that are newly defined in a version of HL7 must not be sent to a receiver that conforms to the older version.
  • A message structure may be declared obsolescent in one release, with a stated alternative message structure. Both the obsolescent message structure and its alternative can be used by all systems supporting that release.
  • The obsolescent message structure may be declared obsolete and dropped when still another HL7 version is issued.
  • An obsolescent message structure may not be declared obsolete for at least two years from the date of the version that first declared it obsolescent.
  • The above notwithstanding, if a new Implementation Technology Specification (ITS) is introduced, HL7 may specify that conformance to the ITS does not require dealing with message structures that are obsolescent when the new ITS is introduced. To the maximum degree possible, these restrictions should not impose limitations on the evolution of the overall reference model. There are no restrictions on making changes to the information model if those changes do not impact the message structures that were described in a prior version of the Standard.

• Determining Conformance: Application roles are the basis for conformance claims. An application role is an abstraction that expresses a portion of the messaging behavior of an information system. Application role names are different than the names generally used to describe healthcare information system products, since they describe messaging interfaces as opposed to application behavior. A typical healthcare information system will probably fill several or many application roles.

  In making a conformance claim, a system developer identifies the application roles to which it wishes to claim conformance. For these application roles, the V3 specification will state directly the trigger events the system shall recognize, messages that the system shall send in response to trigger events or other messages, and the data content of these messages. The specification also states the messages that a system conforming to the application role shall receive and process.

  All conformance claims shall be sufficiently specific to be used as contractual terms in system acquisitions and to be the basis for testing by an independent testing organization.

  User sites may contract with vendors to implement deviations from the HL7 conformance claims. Such arrangements are outside the scope of HL7. Such an arrangement will not be considered a failure of the application to conform to HL7.

  All sequences of messages in V3 shall be related to a trigger event. The trigger event shall be clearly identified in a common field in all messages.

• Confidentiality of Patient Information: It is expected that healthcare application systems that implement V3 will be required to have significantly more functionality to protect the confidentiality of patient information than has been common in the past. The new functions may include, but are not limited to, limiting the right to view or transfer selected data to users with specific kinds of authorization and auditing access to patient data. V3 will seek out and adopt industry security standards that support conveying the necessary information from one healthcare application system to another, so that these systems may perform the confidentiality functions. The Functional Committees, the Control Group, and the Modeling and Methodology Committee shall consult with the Security & Accountability SIG while developing the HL7 Data Model and V3 messages.
• Authenticated Authorization for Services: It is expected that the healthcare application systems that implement V3 will be required to have significantly more functionality to authenticate requests for services and reports of data than has been common in the past. The new functions may include, but are not limited to, electronic signature and authentication of users based on technologies more advanced than passwords. V3 will seek out and reference standards such as X.500 and RFC 1510 to support conveying the necessary information from one healthcare application system to another, so that these systems may perform the authorization and authentication functions. The functional Technical Committees, the Control Group, and the Modeling and Methodology Committee shall consult with the Security & Accountability SIG while developing the HL7 Data Model and V3 transactions.
• Security, Privacy, Non-Repudiation and Integrity: It is expected that the technological platforms upon which V3 information systems developers implement applications that use HL7 will be required to have significantly more capability to protect the confidentiality and integrity of patient information than has been common in the past. The new functions may include, but are not limited to, public- and private-key encryption, and correspondent system authentication and non-repudiation. The Control Group is monitoring these developments to ensure that V3 can be implemented on technological platforms that support these new functions.

What's New with HL7 V3?

• HL7 V3 adopts an Object Oriented (OO) approach using Unified Modeling Language (UML) principles. HL7 employs a completely new development approach with V3. HL7 V3 uses an OO approach that is model and repository-based. This OO approach is supported with trained facilitators, formal education classes, and computerized tools. This approach leads to increased detail, clarity and precision of the specification and finer granularity in the ultimate message. This helps functional committees meet the challenges of de novo interface design, and increases functional breadth and evolution of assumptions. It helps new members become productive in fewer meetings. This is an enormous aid to providing institutional memory and sharing work in progress across committees and to the membership at large.
• HL7 isn't just Level 7 any more! After years of implementing HL7 V2.x, HL7 standard developers realized it was virtually impossible to develop a comprehensive standard without including other levels of the International Organization for Standardization (ISO) Open Systems Interconnect (OSI) Model. Today, committees exist for XML, Security & Accountability, Modeling & Methodology, Arden Syntax, CCOW and Vocabulary.
• Reduced Optionality. Limiting optionality is a primary goal of HL7 V3. Within HL7 V2.x, almost every field is optional. This optionality is necessary since optionality is defined by segment and segments are reused in multiple messages. Declaration of a data field as optional within a segment allows that segment to be used in many different messages without any further definition. However, the wide use of optionality, while helpful in gaining consensus and in writing a somewhat more compact specification, imposes significant costs on interface implementers. In fact, optionality, as a "feature" of HL7 V 2.x, is associated with most of the issues that V3 is trying to solve. Optionality makes it harder to precisely define the semantics of a specific message and makes it virtually impossible to generate conformance claims for messaging.
• Conformance to HL7 V3 will be testable. It is difficult to measure compliance of HL7 V2.x interfaces. Often vendors claim compliance to HL7 without providing any supporting documentation of how they conform. Terms such as HL7-like or HL7-ish are used to describe HL7 interfaces. With HL7 V3, conformance is specified in terms of application roles. Application roles are abstractions that express a portion of the messaging behavior of an information system. A vendor of a healthcare application describes its conformance by asserting that it completely supports all trigger events, messages and data elements associated with one or more application roles. This level of specificity allows clearer pre-contractual understanding between vendors and buyers and will serve as a basis for conformance testing.

Managing HL7 V3 Message Development

This section outlines the procedures used to develop the HL7 V3 messages. These procedures are based on the V3 Methodology and the HL7 Bylaws. The goal is to assure that the standard is developed expediently, appropriately documented, consistent with the requirements for an approval by a balanced consensus, and that it complies with the requirements for certification by the American National Standards Institute (ANSI).

Project Scope Definition

When a functional Technical Committee undertakes a project to develop new normative material in V3 it creates a brief description of the project for approval by the TSC. The project scope statement contains a concise description of the needs to be met by the transactions. This project scope statement is also be used for coordination of projects with other standards organizations. In fact, project scope statements must be reported to the ANSI so that ANSI can fulfill its standards coordination role.¹

Project scope statements are reviewed by the Architectural Review Board (ARB) and must be approved by the HL7 Technical Steering Committee.

HL7 V3 Methodology

The development of V3 messages follows the methodology specified by the HL7 Modeling and Methodology Committee. HL7 may amend the methodology from time to time. The methodology includes a definition of work products delivered by the Technical Committees. Portions of these work products are be designated for three different treatments:

1. included as a normative portion of the eventual standard,
2. included as an informative portion of the eventual standard,
3. not included with the standard, but published with minutes and archived.

The methodology specifies the following requirements. These are annotated to indicate the work products described in the V3 Guide that meet the requirements. The annotations further state whether the work product is normative or informative.

The Modeling and Methodology Committee does not have the right to determine the contents of work products created by the Technical Committees. It serves to facilitate their development, and to negotiate changes among the functional Technical Committees to ensure standard-wide consistency. If disputes cannot be resolved by the Technical Committees and/or the Modeling and Methodology Committee, they shall be resolved by the TSC.

Quality Assurance Process

In order to ensure the highest quality of the work products produced during the course of V3 message development, the HL7 Board of Directors has created the ARB.

The ARB works with the Technical Committees and Modeling and Methodology Committee to define quality measures for the HL7 work products, measure the work products again them, and that adherence to the defined message development process is documented in a manner consistent with HL7 bylaws and procedures. The ARB does not have the right to amend work products or disallow their distribution. It does have the right to include with any work product a statement describing areas where it has determined that the work product has not met established measures of quality.

As a general matter, the ARB is expected to include a statement of its findings in an HL7 general ballot package. However, in order to assist Technical Committees, and to avoid delaying the balloting process, the ARB attempts to make any significant comments as early in the ballot cycle as possible.

Disputes with the findings of the ARB are resolved through the TSC and, if necessary, the Board of Directors.

Getting Started

The Getting Started section provides guidelines and recommendation for how you should approach the HL7 V3 Publication. Each section below depicts a type of HL7 customer based on his or her relationship to the HL7 standard/organization. Locate the type of user that most closely reflects your experience level. The documentation includes recommended reading that will help you build the HL7 V3 knowledge base you desire.

New Implementer

A New Implementer is unfamiliar with HL7 terminology, methodology, and organization. A New Implementer may or may not be a member of the HL7 organization.

Learn the Basics

Learning the basics means becoming familiar with the basic terminology and methodology behind HL7. You would expect to learn the basic principles upon which HL7 V3 was constructed. Upon completion of this use case, you would be prepared to learn more detailed information about V3.

While learning the basics, refer to:

• The Overview sections in the Backbone (this document)
• Glossary
• HL7 V3 Help Guide

Management

Manager

Managers are responsible for hiring qualified HL7 analysts and programmers. They must supervise interface development and implementation efforts. They do not need to understand all of the details of creating an HL7 message, but they need to understand the concepts enough to review contacts, conformance statements, and assess the skills of their team.

Project Manager

The Project Manager is responsible for ensuring the project is completed within budget, on time, and within scope. Project Managers are not interested in all the details of creating an HL7 V3 message, but he needs to understand the concepts enough to review contacts, conformance statements, and assess the skills of his team.

Marketer

A Marketer is responsible for selling HL7 interfaces. He does not need to know the details, but must understand the major concepts and terminology.

Construct Site Agreement

Constructing a site agreement involves creating a specification for two or more parties to communicate using HL7 messages and documents.

When constructing a site agreement, refer to:

• Backbone (this document)
• Glossary
• Refinement, Extension and Conformance to Version 3 document.
• The Interaction Model chapter in the V3 Guide

Sign a Deal

The deal requires HL7 interfaces, so in order to sign it a basic understanding of trigger events and message types, but not a detailed understanding of message fields, is required.

When signing a deal, refer to:

• The What's New in V3? section of the Backbone (this document)
• Refinement, Extension and Conformance to Version 3 document.

Interface Developer

Interface Analyst

Interface Analysts review the interface requirements and write detailed interface specifications.

Interface Programmer

Interface Programmers code and test interface based on the interface specifications.

Develop Interface

Developing an interface requires gathering the interface requirements, analyzing those requirements, developing detailed interface specifications, coding, and testing the interface against the interface specifications and defining the conformance statement.

When developing an interface, you must identify the application section you are working within:

• Health & Clinical Management Section - This includes the Clinical Document Architecture, Medical Records, Public Health Reporting and Regulated Studies domain documents.
• Administrative Management Section - This includes the Accounting and Billing, Claims & Reimbursement, Patient Administration,and Scheduling domain documents.
• Specification Infrastructure / Messaging Section - This includes the Master File / Registry, Message Control Act, Query and Transmission Infrastructure domain documents.
• Common Domains Section - This include the Common Message Element Types and Shared Messages domain documents.

Once you identify the section you can drill down through to the domain messages.

To complete your message development analysis, you will also need to fully understand:

• XML Implementation Technology Specification - The Implementation Technology Specification describes how HL7 messages are sent using a specific method of encoding.
• HL7 Vocabulary Domains - HL7 Vocabulary Domains are concepts you are most likely already familiar with. HL7 Vocabulary Domains are the sets of allowable values for a coded field. For example, if a message contains a marital status field, then the vocabulary domain for that field would consist of the allowed values for that field, such as, single, married, divorced, and separated. Each coded attribute in the RIM will be associated with one and only one vocabulary domain.

For additional reference, be sure to review:

• V3 Glossary
• The Vocabulary chapter and the HL7 Message Components section of the V3 Guide.

HL7 Standard Developer

Standard Developers attend HL7 Working Group Meetings and participate in the creation of the HL7 V3 Standard Specification.

Develop the Standard

Developing the HL7 Standards involves an understanding of the HL7 Organization and its development methods.

Before committing to HL7 Standards development, review:

• the scopes and mission statements of each HL7 Technical Committee and Special Interest Group on the HL7 web site: http://www.hl7.org. This will help you pinpoint to which committee your knowledge and interest will be most compatible.
• V3 Help Guide
• Reference Information Model
• HL7 V3 Data Types: Abstract

Identify the section in which you are most interested.

• Health & Clinical Management Section - This includes the Clinical Document Architecture, Medical Records, Public Health Reporting and Regulated Studies domain documents.
• Administrative Management Section - This includes the Accounting and Billing, Claims & Reimbursement, Patient Administration,and Scheduling domain documents.
• Specification Infrastructure / Messaging Section - This includes the Master File / Registry, Message Control Act, Query and Transmission Infrastructure domain documents.
• Common Domains Section - This include the Common Message Element Types and Shared Messages domain documents.

Once you identify the section you can drill down to the domain messages.

XML Implementation Technology Specification - The XML Implementation Technology Specification defines the representation of HL7 V3 data types and messages in XML, including the method to derive XML DTDs plus additional processing rules from HL7 V3 Hierarchical Message Descriptions (HMDs).

Endnotes

1. [source] The project scope statement should not be confused with the Technical Committee or Special Interest Group charter to which it is related. The TC or SIG charter defines the scope of an HL7 committee and is subject to approval by the HL7 TSC. The key criterion for a project scope statement is that it should be consistent with the charter of the committee that works on it.