A subset definition in which the membership is represented by a set of rules specifying the conditions for inclusion.

### Notes

- The SNOMED CT expression constraint language is the standard way to represent an
*intensional subset definition*of a subset of SNOMED CT concepts. - A row in a Query Specification Reference Set is the standard way to distribute an
*intensional subset definition*of a subset of SNOMED CT concepts.

### Example

An example of an intensional subset definition is

*concepts that are types of respiratory disease characterized by edema*. This is represented as follows in expression constraint language:

< 19829001 |disorder of lung| : 116676008 |associated morphology| = 79654002 |edema|

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