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SNOMED CT  release files contain some concepts  that are not intended for clinical use. These  metadata concepts represent additional information that supports the structure and design of the terminology. All metadata concepts are subtype descendants of the top-level concept   900000000000441003 |SNOMED CT Model Component|.

Concept Enumerations

One use of metadata concepts is to represent enumerated values that can be applied to particular fields in release files and this is known as  concept enumeration.

Concept enumeration is the use of SNOMED CT concept Identifiers to represent of a set of values for a property of a particular type of SNOMED CT component.


  • Concept enumeration serves the same general purpose as more general approaches to providing enumerated lists of values. However, the use of concept identifiers, rather than a sequential or arbitrary set of numbers, allows the human readable meaning of each enumeration to be accessed in the same way as terms associated with clinical concepts. Additionally, use of a hierarchical parent to specify the permitted values, enables the range of values to be updated when necessary.
  • The SNOMED CT concepts used to represent concept enumerations are usually subtype children (or descendants) of a relevant general concept in the SNOMED CT metadata hierarchy. Each possible value is represented by a single child concept.

Other Uses of Metadata

Metadata concepts in other sub-hierarchies of 900000000000441003 |SNOMED CT Model Component| are used for a range of purposes including:

Related Links

For more information, see 4.1 Concept enumerations .