Fig. 2.

Hierarchical structure of the ICF. ICF categories each have a unique code, which is built up of a prefix and a numeric code. Codes included in the different levels are shown for each component. The prefix is a letter indicating the component of which the category is a part: b body functions, s body structures, d activities and participation, and e environmental factors. The numeric code starts with the first level or chapter number (one digit), followed by the second level (two digits), and the third and fourth level (one digit each)