A characteristic that is always true of a concept.
- Defining relationships in the relationship file represent necessary conditions in the inferred view.
If you have a 71620000 |fracture of femur|, the morphological abnormality 72704001 |fracture| must be present. Therefore, 116676008 |morphology| = 72704001 |fracture| is a necessary condition of 71620000 |fracture of femur|.
- Changes introduced in the July 2018 release of the International Edition mean that in future necessary conditions in the stated view will be represented as axioms in the OWL axiom reference set file.