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Top Level Concepts



The immediate subtype children of the root concept represent the most general types of SNOMED CT concepts.

Concept Addition Rules

It is strongly recommended that new top level concepts (i.e. direct subtype children of the root concept) are not added in an extension.

Additional Notes

Top Level Clinical Hierarchies



These concepts represent a distinct type of clinical concept

Concept Addition Rules

Subtype descendants of the top level clinical concepts may be added in an extension.

Additional Notes

Concepts added in these hierarchies should conform with:

  • Concept model rules applicable to the relevant concept domain
  • Quality standards applicable to all SNOMED CT clinical content.

These concepts should be classified to generate a set of inferred relationships in necessary normal form, for inclusion in the extension distribution files.

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