tuberculosis of meninges (disorder)
tuberculoma of meninges (disorder)
tuberculosis of cerebral meninges (disorder)
tuberculosis of spinal meninges (disorder)
tuberculous abscess of epidural space (disorder)
tuberculous leptomeningitis (disorder)
tuberculous arachnoiditis (disorder)
tuberculous meningoencephalitis (disorder)
With the help of the SNOMED CT hierarchy (as shown in ), this same subset can be defined intensionally as:
The expansion of an intensional subset defined using this query is the same as the extensionally defined subset shown above.
Expansion derived from SNOMED CT International Edition, dated 20170131.
As can be seen, the results of this lexical query only includes 3 of the possible 8 4 values from the previous subset. In other cases, lexical queries may incorrectly find concepts which are not appropriate to the subset. It is therefore recommended that lexical queries are avoided in the definition of intentional subsets. However, they do serve a useful purpose in identifying candidates for an otherwise manually crafted subset.
Extensional subsets are commonly defined in SNOMED CT using a Simple reference set - however an Ordered reference set or Annotation reference set can be used if additional information needs to be recorded for each member of the subset. Intensional subsets are defined in SNOMED CT using a Query specification reference set. A Query specification reference set allows a serialized query to define the membership of a subset of SNOMED CT components. It also specifies the extensional reference set into which the results of executing the query are generated. Intensional reference sets are preferred in many circumstances as they enable their membership to be automatically recomputed over new versions of SNOMED CT. Version management of subsets is discussed further in section section 11.4 Versioning.
Subsets can be created using the following methods, either alone or in any combination: