Overview

Concepts can be added to an extension, either to address content gaps or to expand the scope of SNOMED CT to include concepts that are used locally.

Concepts in an extension follow the same logical design as concepts in the International Edition. They are distributed in a concept file, which follows the standard RF2 concept release file format. Additionally, descriptions and relationships associated with extension concepts should be represented in separate description and relationship files. Please refer to the section on authoring for more details on the principles for authoring components in an extension.

Attributes

In the case of concepts, one additional attribute is used with the four common attributes.

definitionStatusId

The attribute definitionStatusId is used to state whether a concept is primitive or fully defined. Initially this is set to | Primative|  because it is not possible for a concept to be | Defined|  until its defining relationships have been added. If the defining relationships of a concept are found to be sufficient to fully define the concept, the definitionStatusId can then be updated to reflect this.

Example

In below, a row associated with the concept 5281000124103 | Persistent asthma|  from the concept table of the US edition, 2070901 is presented. Note that the attribute values in this row have been set according to the rules previously described.

Key points as follows

• The namespace identifier in the id uses a namespace owned by the National Library of Medicine which indicates this concept was originally created by the US NRC
  • The partition identifier is “10” so we know this concept originated in an extension
• The moduleId indicates that this concept is included in the | US National Library of Medicine maintained module| , which is a module in the US Edition
• The definitionStatusId states that this is a | Primative|  concept