Sanctioned specialisation

a mechanism for extending the content of a controlled terminology system by combining existing components of the system using specific mechanisms also defined in the system.

An example: pneumonia can be described as a special type of inflammation: Inflammation which has_location Lung and this can be further specialised into pneumococcal pneumonia (caused by pneumococcus) Inflammation which has_location Lung is_caused_by Pneumococcus

Sanctioned specialisation is used in description logic systems such as SNOMED CT. The concept is defined in a broader context and more exapmles given in ISO 17115, an ISO standard.