4.3.1.0.4 Display Terms for Specific Languages
In the ValueSet resource any number of terms ('designations 
') in additional languages and dialects can be specified for a particular concept in a value set definition using the ValueSet.compose.include.concept.designation element. The language is specified as a BCP-47 language code as required by the 'designation.language ' element, with the value taken from the 'languageCode' field of the RF2 Descriptions file ('languageCode' is ISO-639-1, a subset of BCP-47). BCP-47 private use extensions can be used to specify the SNOMED CT language reference set of a term. The form for these extensions is <lang>-x-sctlang-<language reference set ID>, for example en-x-sctlang-90000000-00005090-07 corresponds to the US English language reference set. The SNOMED CT Expression Constraint Language specification also lists a number of aliases for language reference sets which may be used: Dialect Aliases. The type of the term (e.g., the SNOMED CT code for "Fully specified name", "Synonym" or "Definition") can be specified in 'designation.use '.
[Note that ValueSet.compose.include.concept is only used when the value set is defined extensionally (i.e. as an enumerated list of concepts). For intensionally-defined value sets (i.e. using one or more filters) additional terms could be added using CodeSystem.concept.designation, as noted below.]
The CodeSystem resource can also similarly be used to specify additional terms ('designations ') for a concept using the CodeSystem.concept.designation element (the additional terms may be from a published national or other localized SNOMED CT edition or provided in a code system supplement ). If supported by the terminology server, the additional terms are available to be returned in a value set expansion (controlled by the $expand operation 'includeDesignations' input parameter).