In 1980, Wood developed a framework for the World Health Organization that provides an international standard for disability data. In this framework, the concept of disability as encompassing impairments, disabilities, and handicaps. Impairment in this case denoted any loss or abnormality in physiologic or anatomic structure or function. Disability indicated any restriction or inability (resulting from an impairment) to performance activity in the manner considered normal for that individual. Handicap was defined as any disadvantage (resulting from an impairment or disability) that limits the fulfillment of normal role behavior for the individual.

Wood PHN. Appreciating the consequences of disease: the International Classification of Impairments, Disabilities, and Handicaps. WHO Chronicle 34:376-380, 1980