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Concept reference

The ability to reference a precoordinated SNOMED CT concept using its identifier and optional human-readable term.

Concept hierarchy

The ability to refer to a set of concepts which is exactly equal to the descendants, descendants and self, ancestors, or ancestors and self of a given concept.

Immediate children and parents

Conjunction

The ability to connect two expression constraints, attribute groups or attribute sets via a logical AND operator.

Disjunction

The ability to connect two expression constraints, attribute groups or attribute sets via a logical OR operator.

Refinement

The ability to refine (or specialize) the meaning of an expression constraint using one or more attributes values.

Attribute group

The ability to group a collection of attributes which operate together as part of a refinement.

Attribute

The ability to specify an attribute name-value pair which further refines the meaning of the matching expressions.

Attribute descendants

The ability to define an attribute which may apply to either the descendants of the given attribute name, or the descendants and self of the given attribute name.

Nesting

The ability to include an expression constraint as the value of an attribute.

Concrete values

The ability to use integers, decimals and strings as attribute values.

Concrete value comparison

The ability to compare the attribute value of the matching expressions with the attribute value in the expression constraint using mathematical comparison operators (e.g. =, <, >, <=, >=, !=).

Member of

The ability to refer to a set of concepts that are referenced by members of a reference set (or set of reference sets).

Exclusion

The ability to filter out a set of expressions from the result, by either removing expressions whose focus concept is in a specific set, or removing expressions whose attribute value matches a given value.

Any

The ability to refer to any concept in the substrate, without relying on the availability of a single root concept