HL7 CDA Core Principles: Unterschied zwischen den Versionen

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(XML representation of data types)
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Actual data is mostly carried in HL7 Version 3 by populating XML attributes and not as element content. Exceptions are names of persons and organizations as well as addresses.
 
Actual data is mostly carried in HL7 Version 3 by populating XML attributes and not as element content. Exceptions are names of persons and organizations as well as addresses.
 
The XML elements have names like the model attributes. For example, a model attribute “id” has a corresponding XML element named <id…>. The model determines the sequence of elements and their hierarchy. The data type itself determines the XML attributes within the start tag. The notation here is as follows:
 
The XML elements have names like the model attributes. For example, a model attribute “id” has a corresponding XML element named <id…>. The model determines the sequence of elements and their hierarchy. The data type itself determines the XML attributes within the start tag. The notation here is as follows:
 +
{| class="hl7table"
 +
|+
 +
! Attributte !! DT !! Conf !! Description
 +
|-
 +
| (name of the model attribute or XML el-ement) || Data type || Conformance, i.e. O, R, M || Textual description
 +
|}
  
 +
XML attributes (data type properties) are denoted as @attribute in order to distinguish their names from XML elements.
 +
Example: in the example model above, the data type of the id attribute's is II (Instance Identifier). The corresponding XML attributes for that data type include @root and @extension.
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<center><span style="font-size:88%">''XML Example snippet''</span></center>
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<syntaxhighlight lang="xml">
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<id  root="…"  extension="..." />
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</syntaxhighlight>
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A description of the data types and their corresponding XML representation is contained in subsequent paragraphs of this guide.
  
 
==== Exceptions using XML element content ====
 
==== Exceptions using XML element content ====

Version vom 13. Juni 2019, 15:58 Uhr

Introduction

This implementation guide specifies the Core Principles of using the Clinical Document Architecture [1].

Scope

This guide focuses on Data Types Release 1 [2]. Meanwhile an ISO specification ISO 21090 is out, also known as Data Type Release 2. The latter is subject to another im-plementation guide that will be published when ISO data types are used.

Focus of this document: HL7 Version 3 Data Types for CDA

The following chapters of this document will focus on the description of the data types and associated material. It will highlight the essentials in four chapters, all focusing on the Norwegian situation.

  • Common aspects: explains common aspects of use of CDA and XML
  • Data types: gives an overview and detailed specification of all data types used in CDA
  • Identification schemes: explains major aspects of identification and the use in CDA
  • Use of vocabulary: explains major aspects of vocabulary use in CDA.

Background

In many (European) countries, implementation guides for the use of data types in HL7 V3 are published. They take into account country specific constraints on the data types.

Legend of symbols

In this document several symbols are used.

Pfeil rechts.png This is an important item
Issue.svg This is a known open issue
Faq.svg This is a frequently asked question (FAQ) with answer
Conformance.svg This is a constraint; in some situations also the rule identification is specified, e.g. dtr1-1-ANY, which links to the corresponding validation rule.

Version history

Version Date Description Author
1.1 2019-04-24 Refurnished guide based on earlier work Kai U. Heitmann

Common aspects

Use of XML

HL7 Version 3 CDA uses the Extensible Markup Language (XML) as the exchange for-mat. It is assumed that the reader is familiar with common XML aspects. However, some constraints are made regarding the use of CDA.

Character Set

XML Example snippet
<?xml version="1.0" encoding="utf-8"?>

CDA document structure

The XML namespace for CDA Release 2 documents is urn:hl7-org:v3. This must be correctly mentioned in every XML instance. CDA XML documents starts with the root element ClinicalDocument.

XML Example snippet
<ClinicalDocument xmlns="urn:hl7-org:v3" xmlns:voc="urn:hl7-org:v3/voc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchemma-instance">

    <!-- CDA Header --> 
          ...
    <!-- CDA Body -->
    <component>
        <structuredBody>
           ...
        </structuredBody>
    </component>

</ClinicalDocument>

Data types

Introduction

The following chapter describes the typical data types used in CDA implementation guides. For further information please refer to the HL7 V3 standard and its two parts concerning data types:

  • Abstract Data type definition [3]
  • XML ITS for data types [4]

Data types are properties of model class attributes and the basic building blocks of in-formation in a CDA XML instance. For example, a model attribute named “time” has as its data type a time stamp “TS” (see Figure 1).

CDA Core Principles Figure 1 CDA Structure Data Types.png

[Abbildung 1] CDA structure (left) and the data type specification (right)

XML representation of data types

Actual data is mostly carried in HL7 Version 3 by populating XML attributes and not as element content. Exceptions are names of persons and organizations as well as addresses. The XML elements have names like the model attributes. For example, a model attribute “id” has a corresponding XML element named <id…>. The model determines the sequence of elements and their hierarchy. The data type itself determines the XML attributes within the start tag. The notation here is as follows:

Attributte DT Conf Description
(name of the model attribute or XML el-ement) Data type Conformance, i.e. O, R, M Textual description

XML attributes (data type properties) are denoted as @attribute in order to distinguish their names from XML elements. Example: in the example model above, the data type of the id attribute's is II (Instance Identifier). The corresponding XML attributes for that data type include @root and @extension.

XML Example snippet
<id   root="…"   extension="..." />

A description of the data types and their corresponding XML representation is contained in subsequent paragraphs of this guide.

Exceptions using XML element content

Combined data types

Conformance information

Missing values (null flavor)

ANY as the generic data type

Boolean (BL)

Instance Identifier (II)

Encapsulated Data (ED)

Strings (ST)

Concept Descriptor (CD)

Coded with Equivalents (CE)

Coded Value (CV)

Coded Simple Value (CS)

Telecommunication Address (TEL)

Postal Address (AD)

Person Name (PN)

Organisation Name (ON)

Integer Number (INT)

Physical Quantities (PQ)

Point in Time (TS)

Intervals (IVL)

Interval of time (IVL_TS)

Interval of physical quantities (IVL_PQ)

Ratio of quantities (RTO_QTY_QTY)

Identification mechanisms

Object Identifiers (OIDs)

Instance identification

Coding scheme identification

List of identification schemes

List of code systems

Vocabulary

Code Systems

Value Sets

Appendix

References

  1. Clinical Document Architecture Release 2 http://www.hl7.org
  2. HL7 Data Types Release 1 http://www.hl7.org
  3. HL7 Version 3 Abstract Data type definition http://www.hl7.org
  4. XML ITS for data types http://www.hl7.org

List of figures

  1. CDA structure (left) and the data type specification (right)