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Member of

The memberOf function (by default) evaluates to the set of concepts that are referenced by the given reference set (i.e. the set of referencedComponentIds). Please note that this function may be applied only to reference sets whose referenced components are concepts. The SNOMED CT Expression Constraint Language does not support use of the memberOf function on reference sets whose referencedComponents are not concepts (i.e. descriptions or relationships).

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	^ 700043003 |Example problem list concepts reference set |

Using the long syntax the expression constraint is represented as:

	memberOf 700043003 |Example problem list concepts reference set|

The expression constraints above both return the values in the referencedComponentId field of the given reference sets. However, it is also possible to specify one or more fields, whose values will be returned, by including the relevant field names is square brackets after the memberOf operator ("^" or "memberOf"). For example, the following expression constraint is equivalent to the brief syntax example above.

	^ [referencedComponentId] 700043003 |Example problem list concepts reference set|

The value of other fields can also be returned by an expression constraint

. For example, the following expression constraint will return the targetComponentId values (i.e. the 'Entire' anatomy concepts) from the 

	^ [targetComponentId] 734138000 |Anatomy structure and entire association reference set|

It is also possible to return the values of more than one field in a reference set (e.g. a pair or tuple of values).

For example, to return both the source and target of the 

	^ [referencedComponentId, mapTarget] 816210007 |SNOMED CT to MedDRA simple map reference set|

To return all the non-metadata fields of a referenceSet (i.e. the values of the referencedComponentId and additional fields), a wildcard (i.e. "*" in the brief syntax, and "*" or "Any" in the long syntax) can be used. For example, the following expression constraint will return the referencedComponentId, mapGroup, mapPriority, mapRule, mapAdvice, mapTarget and correlationId for each row of the 

	^ [*] 447562003 |ICD-10 complex map reference set|

For more information on the use of reference set field names in ECL, please refer to Appendix E - Reference Set Fields.

Please note that it is also possible to apply the memberOf function to an expression constraint that returns a set of concept-based reference set concepts. For more information, please refer to 6.7 Nested Expression Constraints.

And for information about applying filter constraints to reference set members, please refer to 6.10 Member Filters.

Any

A single 'star' (i.e. "*") may be used in the place of a concept reference to represent any concept in the substrate. The expression constraint below evaluates to the set of all concepts in the given substrate.

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	^ *

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