Overview
Each 
has a 
.
Requirements and Options
describes several distinct types of access to concept definitions and the client application functionalities that each of these access types supports.
General purpose terminology services that are able to access 
relationships can be used to meet a limited set of SNOMED CT use cases. However, SNOMED CT terminology services should also provide access to the 
of concept definitions.
Advanced SNOMED CT terminology services require the ability to access and interpret the 
that represent the 
of concept definitions. They should also enable description logic classification either as a built in service or via an interface to separate classifier. Services that support classification provide added value for data retrieval and analysis by enabling post-coordinated expressions to be classified and appropriately located in the subtype hierarchy.
The required services listed in 
omit services that only require access to subtype relationships, as these are described in 4.5 Get and Test Concept Subtypes and Supertypes.
Practical Requirements for Access to Concept Definitions |
| Terminology Service Access to Definitions | Client Application Functionality Supported |
Access to : | Display subtype hierarchy 
|
Access to the  of : | Testing subsumption between concepts 
|
| Display of inferred concept definition 
Postcoordinated expression creation
Expression constraint and query creation 
|
Access to the complete of concept definitions, as  | Display of stated concept definition
Terminology authoring
Terminology classification 
Expression classification - Applying description logic to classify an
 to enable appropriate subsumption testing when reporting records that include 
|
Interdependencies
Required By
Depends On
Service Examples
The Snowstorm and FHIR examples are presented in plain text and URL encoded versions. Always use the "Encoded URL" when testing the example service requests. The plain text version is included to aid readability but using this version in a service request may result in errors. These errors result from characters that have to be encoded as they are not permitted in a URL (see IETF RFC1738). |
| Service Name | API Call | Result |
Get the inferred necessary normal form definition of a concept |
GET [snowstorm]/[branch]/concepts/[conceptId]/normal-form?includeTerms=[true|false] |
for example GET [snowstorm]/MAIN/2020-01-31/concepts/6025007/normal-form?includeTerms=true |
or without including the terms GET [snowstorm]/MAIN/2020-01-31/concepts/6025007/normal-form |
| Returns a JSON data object containing a compositional grammar expression representing the inferred definition of the concept. If the optional includeTerms parameter is set to true the expression includes the fully specified names of each concept referenced in the expression. Otherwise only the expression only includes the concept identifiers. |
| Get the stated definition of a concept |
GET [snowstorm]/MAIN%2F2020-01-31/members?referenceSet=733073007&referencedComponentId=[conceptId] |
for example GET [snowstorm]/MAIN%2F2020-01-31/members?referenceSet=733073007&referencedComponentId=6025007 |
or as example of a concept defined by more than one axiom GET [snowstorm]/MAIN%2F2020-01-31/members?referenceSet=733073007&referencedComponentId=473011001 |
| This service returns a JSON representation of one or more members of in the OWL expression reference set that together represent the stated definition of the identified concept. Each of these reference set members contains an axiom, represented using  , in the additionalFields.owlExpression property string.
|
| Service Name | API Call | Result |
Get the inferred necessary normal form definition of a concept
|
[fhir]/CodeSystem/$lookup?system=http://snomed.info/sct&code=[conceptId]&property=normalForm&_format=json |
for example GET [fhir]/CodeSystem/$lookup?system=http://snomed.info/sct&code=6025007&property=normalForm&_format=json |
| Returns a JSON representation of information containing the definition of the concept. The data returned includes the necessary inferred, normal form definition of the concept represented as a compositional grammar expression. |
| Get the stated definition of a concept | N/A | This service is not supported by the FHIR terminology services API |
| Service Name | SQL Query  | Result |
Get the inferred necessary normal form definition of a concept |
-- Get inferred defining relationships
SELECT typeId,destinationId,group
FROM snap_relationship
WHERE AND active=1 AND sourceId=[conceptId]
AND characteristicType=900000000000011006; |
for example -- Get inferred defining relationships
SELECT typeId,destinationId,group
FROM snap_relationship
WHERE active=1 AND characteristicType=900000000000011006
AND sourceId=6025007; |
or including terms
-- Get inferred defining relationships with terms
SELECT
CONCAT(typeId,"|",typeTerm,"|=",
destinationId,"|",destinationTerm,"|") 'value',
relationshipGroup 'group'
FROM snap_rel_def_fsn
WHERE sourceId=6025007; |
| Returns the set of rows each containing one defining relationship with its associated relationship group number. |
| Get the stated definition of a concept |
-- Get stated defining axioms
SELECT owlExpression
FROM snap_refset_owlexpression
WHERE active=1 AND refsetId=733073007
AND referencedComponentId=[conceptId]
ORDER BY owlExpression; |
for example -- Get stated defining axioms
SELECT owlExpression
FROM snap_refset_owlexpression
WHERE active=1 AND refsetId=733073007
AND referencedComponentId=6025007
ORDER BY owlExpression; |
or as example of a concept defined by more than one axiom -- Get stated defining axioms
SELECT owlExpression
FROM snap_refset_owlexpression
WHERE active=1 AND refsetId=733073007
AND referencedComponentId=473011001
ORDER BY owlExpression; |
| Returns the set of rows each containing one OWL axiom. The sort order used in this query ensures that class axioms appear before any GCI axioms |
|
- only includes services that access the
 or  of a complete concept definition. Services that access subtypes and supertypes of concepts are described in 4.5 Get and Test Concept Subtypes and Supertypes. - The
 refers to the logical form in which inferred concept definitions are represented in the relationships file. This form is unable to represent some of the axioms present in the enhanced description logic supported by OWL expressions in the stated view of some concept definitions. - Language and/or dialect should be specified if the service returns terms associated with referenced concepts.
- For details of SNOMED CT compositional grammar expressions see Compositional Grammar - Specification and Guide.
- In the Snowstorm service requests [snowstorm] should be replaced by the URL to the Snowstorm server endpoint.
- In the FHIR service requests [fhir] should be replaced by the URL to the FHIR terminology server endpoint. FHIR® is a registered trademarks of HL7 (www.hl7.org).
- The SNOMED CT MySQL example database is not designed as a terminology server and is not intended for use in a live system . It is referenced in this guide as an illustration that some readers may find helpful. For more information about the SNOMED CT example database see the SNOMED CT - SQL Practical Guide. For instructions on how to build the example database refer to Appendix A: Building the SNOMED CT Example Database.
- For more information about the differences between SubClass axioms and GCI axioms see General Concept Inclusions - GCIs in the Editorial Guide.
|