public interface CD extends ANY
A concept descriptor represents any kind of concept usually by giving a code defined in a code system. A concept descriptor can contain the original text or phrase that served as the basis of the coding and one or more translations into different coding systems. A concept descriptor can also contain qualifiers to describe, e.g., the concept of a "left foot" as a postcoordinated term built from the primary code "FOOT" and the qualifier "LEFT". In cases of an exceptional value, the concept descriptor need not contain a code but only the original text describing that concept.
The concept descriptor is mostly used in one of its restricted or profiled forms, CS, CE, CV.
Use of the full concept descriptor data type is exceptional. It requires a conscious decision and documented rationale. In all other cases, one of the CD restrictions shall be used.
The advantage of the concept descriptor data type is its expressiveness, however, if all of its features, such as coding exceptions, text, translations and qualifiers are used at all times, implementation and use become very difficult and unsafe. Therefore, the CD type is most often used in a restricted form with reduced features.
All CD restrictions constrain certain properties of the CD. Properties may be constraint to the extent that only one value may be allowed for that property, in which case mentioning the property becomes redundant. Constraining a property to one value is referred to as suppressing that property. Although, conceptually a suppressed property is still semantically applicable, it is safe for an HL7 interface to assume the implicit default value without testing.
| Modifier and Type | Method and Description |
|---|---|
ST |
code()
The plain code symbol defined by the code system.
|
UID |
codeSystem()
Specifies the code system that defines the code.
|
ST |
codeSystemName()
The common name of the coding system.
|
ST |
codeSystemVersion()
If applicable, a version descriptor defined specifically for the given
code system.
|
ST |
displayName()
A name or title for the code, under which the sending system shows the
code value to its users.
|
BL |
implies(CD x)
This operation on the HL7 Data Type is not supported in the current
version of HDR.
|
ED |
originalText()
The text or phrase used as the basis for the coding.
|
LIST<CR> |
qualifier()
Specifies additional codes that increase the specificity of the the
primary code.
|
SET<CD> |
translation()
This operation on the HL7 Data Type is not supported in the current
version of current version of HDR.
|
dataType, equal, isNull, nonNull, notApplicable, nullFlavor, other, unknownST code()
The plain code symbol defined by the code system. For example, "784.0" is the code symbol of the ICD-9 code "784.0" for headache.
A non-exceptional CD value has a non-NULL code property whose value is a character string that is a symbol defined by the coding system identified by the codeSystem property. Conversely, a CD value without a value for the code property, or with a value that is not from the cited coding system is an exceptional value (NULL of flavor other).
ST displayName()
A name or title for the code, under which the sending system shows the code value to its users.
The display name is included both as a courtesy to an unaided human interpreter of a code value and as a documentation of the name used to display the concept to the user. The display name has no functional meaning; it can never exist without a code; and it can never modify the meaning of the code.
NOTE: HL7 offers a "print name" in it's predefined vocabulary domains. These values are suitable for use in the displayName.
NOTE: Display names may not alter the meaning of the code value. Therefore, display names should not be presented to the user on a receiving application system without ascertaining that the display name adequately represents the concept referred to by the code value. Communication must not simply rely on the display name. The display name's main purpose is to support debugging of HL7 protocol data units (e.g., messages.)
UID codeSystem()
Specifies the code system that defines the code.
Code systems shall be referred to by Unique Identifier (UID). The UID allows unambiguous reference to standard HL7 codes, other standard code systems, as well as local codes. HL7 shall assign an UID to each of its code tables as well as to external standard coding systems that are being used with HL7. Local sites must use their ISO Object Identifier (OID) to construct a globally unique local coding system identifier.
Under HL7's branch, 2.16.840.1.113883, the sub-branches 5 and 6 contain HL7 standard and external code system identifiers respectively. The HL7 Vocabulary Technical Committee maintains these two branches.
A non-exceptional CD value (i.e. a CD value that has a non-null code property) has a non-NULL code system specifying the system of concepts that defines the code. In other words whenever there is a code there is also a code system.
NOTE: although every non-NULL CD value has a defined code system, in some circumstances, the ITS representation for the CD value needs not explicitly mention the code system. For example, when the context mandates one and only one code system to be used specifying the code system explicitly would be redundant. However, in that case the code system property assumes that context-specific default value and is not NULL.
ST codeSystemName()
The common name of the coding system.
The code system name has no computational value. The purpose of a code system name is to assist an unaided human interpreter of a code value to interpret the code system UID. It is suggested &ldash; though not absolutely required &ldash; that ITS provide for code system name fields in order to annotate the UID for human comprehension.
HL7 systems must not functionally rely on the code system name. The code system name can never modify the meaning of the code system UID value and cannot exist without the UID value.
ST codeSystemVersion()
If applicable, a version descriptor defined specifically for the given code system.
HL7 shall specify how these version strings are formed for each external code system. If HL7 has not specified how version strings are formed for a particular coding system, version designations have no defined meaning for such coding system.
Different versions of one code system must be compatible. Whenever a code system changes in an incompatible way, it will constitute a new code system, not simply a different version, regardless of how the vocabulary publisher calls it.
For example, the publisher of ICD-9 and ICD-10 calls these code systems, "revision 9" and "revision 10" respectively. However, ICD-10 is a complete redesign of the ICD code, not a backward compatible version. Therefore, for the purpose of this data type specification, ICD-9 and ICD-10 are different code systems, not just different versions. By contrast, when LOINC updates from revision "1.0j" to "1.0k", HL7 would consider this to be just another version of LOINC, since LOINC revisions are backwards compatible.
ED originalText()
The text or phrase used as the basis for the coding.
The original text exists in a scenario where an originator of the information does not assign a code, but where the code is assigned later by a coder (post-coding.) In the production of a concept descriptor, original text may thus exist without a code.
NOTE: Although post-coding is often performed from free text information, such as documents, scanned images or dictation, multi-media data is explicitly not permitted as original text. Also, the original text property is not meant to be a link into the entire source document. The link between different artifacts of medical information (e.g., document and coded result) is outside the scope of this specification and is maintained elsewhere in the HL7 standards. The original text is an excerpt of the relevant information in the original sources, rather than a pointer or exact reproduction. Thus the original text is to be represented in plain text form.
LIST<CR> qualifier()
Specifies additional codes that increase the specificity of the the primary code.
The primary code and all the qualifiers together make up one concept. A concept descriptor with qualifiers is also called a code phrase or postcoordinated expression.
Qualifiers constrain the meaning of the primary code, but cannot negate it or change it's meaning to that of another value in the primary coding system
Qualifiers can only be used according to well-defined rules of post-coordination. A value of type CD may only have qualifiers if it's code system defines the use of such qualifiers or if there is a third code system that specifies how other code systems may be combined.
SET<CD> translation()
A set of other concept descriptors that translate this concept descriptor into other code systems.
The translation property is a set of other concept descriptors that each translate the first concept descriptor into different code systems. Each element of the translation set was translated from the first concept descriptor. Each translation may, however, also contain translations. Thus, when a code is translated multiple times the information about which code served as the input to which translation will be preserved.
NOTE: the translations are quasi-synonyms of one real-world concept. Every translation in the set is supposed to express the same meaning "in other words." However, exact synonymy rarely exists between two structurally different coding systems. For this reason, not all of the translations will be equally exact.
UnsupportedOperationExceptionBL implies(CD x)
Specifies whether this concept descriptor is a specialization of the operand concept descriptor.
Naturally, concepts can be narrowed and widened to include or exclude other concepts. Many coding systems have an explicit notion of concept specialization and generalization. The HL7 vocabulary principles also provide for concept specialization for HL7 defined value sets. The implies-property is a predicate that compares whether one concept is a specialization of another concept, and therefore implies that other concept.
When writing predicates (e.g., conditional statements) that compare two codes, one should usually test for implication not equality of codes.
UnsupportedOperationExceptionHDR Glossary HDR Concept Lists HDR Exceptions HDR Programmer's Guide HDR Implementation Guide HDR Profile Options
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