| Hierarchy | 900000000000442005 | Core metadata concept| |
| Purpose | This concept is the supertype for metadata used directly by SNOMED CT components. |
| Concept Addition Rules | No new subtype children may be added in an extension. See tables below for concept addition rules for each of the subtypes of 900000000000442005 | Core metadata concept| . |
| Hierarchy | 900000000000449001 | Characteristic type| |
| Purpose | This subhierarchy provides the values for Relationship.characteristicTypeId. |
| Examples | |
| Concept Addition Rules | No new subtype descendants may be added in an extension. |
| Hierarchy | 900000000000444006 | Definition status| |
| Purpose | This subhierarchy provides the values for Concept.definitionStatusId |
| Examples | |
| Concept Addition Rules | No new subtype descendants may be added in an extension. |
| Hierarchy | 900000000000446008 | Description type| |
| Purpose | This subhierarchy provides the values for Description.typeId |
| Examples | |
| Concept Addition Rules | Additional types permitted provided these are additive and do not replace the synonym or fully specified name values |
| Concept Addition Uses Cases |
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| Hierarchy | 900000000000450001 | Modifier| |
| Purpose | This subhierarchy provides the values for Relationship.modifierId |
| Examples | |
| Concept Addition Rules | No new subtype descendants may be added in an extension. |
| Hierarchy | 900000000000443000 | Module| |
| Purpose | This subhierarchy provides the concepts used to identify modules |
| Examples | |
| Concept Addition Rules | The addition of modules that form part of the extension is required. These new module concepts must either be direct children of 900000000000443000 | Module| or descendants of a child of 900000000000443000 | Module| that is owned by the same extension provider. It is not permitted to add modules as subtypes of modules maintained by another extension provider. Each module concept added within an extension must have an identifier that contains the extension's namespace identifier. |
| Concept Addition Uses Cases | The addition of at least one module concept is essential for all extensions. More than one module concept may be added to enable content to be organized into separate modules. |