| Hierarchy | 900000000000454005 | Foundation metadata concept| |
| Purpose | This concept is a supertype for metadata used to support SNOMED CT reference sets. |
| 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 900000000000454005 | Foundation metadata concept| |
| Hierarchy | 900000000000455006 | Reference set| |
| Purpose | The subtype children represent reference set types. Subtype descendents represent either reference sets of the type specified by their supertype parent or groups of reference sets of a type specified by their supertype parent. |
| Examples | Reference set types
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| Concept Addition Rules | New subtype children may be added in an extension, as long as they represent a new and distinct Reference Set Type (i.e. not an individual reference set). New subtype descendants may be added in an extension, as long as they represent a Reference Set of the type defined by its supertype ancestors. |
| Concept Addition Uses Cases |
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| Additional Notes | When a new reference set type is defined, an appropriate set of reference set descriptor rows must be created in the reference set descriptor reference set to specify the order and format of the reference set columns. Furthermore, the intended use and format of the new reference set type must also be documented. Appropriate documentation should also be provided to describe the specific use of each individual reference set. The addition of reference set descriptor rows for individual reference sets is also recommended. However, this is optional if there are no additional constraints over and above those specified for its reference set type. |
| Hierarchy | 900000000000457003 | Reference set attribute| |
| Purpose | The subtype children represent named attributes used to represent columns in reference sets. Also includes two special subtypes: 900000000000459000 | Attribute type| and 900000000000491004 | Attribute value| which are separately documented. |
| Examples | |
| Concept Addition Rules | Subtype children can be added in an extension to represent new column names for use in additional reference set type definitions. See separate notes on subtype descendance of the special subtypes 900000000000459000 | Attribute type| and 900000000000491004 | Attribute value| |
| Hierarchy | 900000000000459000 | Attribute type| |
| Purpose | These concepts represent data types associated with reference set attributes. |
| Examples |
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| Concept Addition Rules | No new subtype children or subtype descendants may be added in an extension. If new subtypes are required these should be requested for addition to the International Edition. |
| Hierarchy | 900000000000491004 | Attribute value| |
| Purpose | These concepts represent values that can be applied to specified columns in a reference set. |
| Concept Addition Rules | Additional subtype children may be added in an extension to represent values applicable to a newly added reference set or reference set type. Subtype descendants should not be added in an extension, except where they are descendants of a subtype child added to support a newly added reference set. |
| Potential Problems | Adding subtype descendant to pre-existing subtype children would have the effect of changing the permitted value set for a pre-existing reference set type and reference sets defined as having that type. |