This file provides a standardized way of associating alternate Identifiers from various schemes with SNOMED CT components .
At any point in time, an alternate Identifier within a particular scheme will be associated with one and only one SNOMED CT component. A SNOMED CT component may be associated with zero or more alternate Identifiers within a single scheme.
It is important to note that the SNOMED CT component and its alternate Identifiers all identify precisely the same real-world object.
Note: The Identifier file is not currently used in the SNOMED CT International Release as use of the more flexible Simple map type references set structure is preferred for links to alternative codes. The only known current use of this file is for internal identification of components during the content development process.

Table 12. Identifier file - Detailed Specification

 

 

 

Field

Data type

Immutable

Purpose

 

identifierSchemeId

SCTID

Y

Identifier of the concept enumeration value from the Metadata hierarchy that represents the scheme to which the Identifier value belongs. Set to a descendant of 900000000000453004 $$ Identifier scheme $$ within the metadata hierarchy .

 

alternateIdentifier

String

Y

String representation of the alternate Identifier in its native scheme.

 

effectiveTime

Time

N

Specifies the inclusive date at which the alternate Identifier was associated with the SNOMED CT component .

 

active

Boolean

N

Specifies whether the association was active or inactive from the point in time specified by the effectiveTime .

 

moduleId

SCTID

N

Identifies the source module that this association was created in. Set to a child of 900000000000443000 $$ Module $$ within the metadata hierarchy .

 

referencedComponentId

SCTID

Y

Uniquely identifies the SNOMED CT component with which the alternate Identifier is associated.

 

Only one record with the same identifierSchemeId and alternateIdentifier fields will be current at any point in time. The current record will be the one with the most recent effectiveTimebefore or equal to the point in time under consideration.
If the active field of this record is false ('0'), then the association is inactive at that point in time. If the active field is true ('1'), then there is an identity at that point in time between the referencedComponentId (a SNOMED CT component) and the alternateIdentifier in the scheme identified by identifierSchemeId .
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