Related classifications are those that partially refer to reference classifications, or are associated with the reference classification at specific levels of structure only.

ICECI: International Classification of External Causes of Injuries

ISO 9999: Technical aids for persons with disabilities - Classification and terminology

ATC/DDD: The Anatomical Therapeutic Chemical Classification System with Defined Daily Doses

ICPC-2: International Classification of Primary Care, 2nd edition

ICNP: International Classification for Nursing Practice