The Social Security Administration maintains a medical listing of impairments which it considers severe enough to keep a claimant from performing work at a substantial gainful activity level. This listing is known as the "Blue Book", and it contains disabling mental and physical health conditions for fourteen major body systems (ex. respiratory, mental disorders, musculoskeletal, etc.). Conditions in the Social Security Administration's List of Impairments are generally considered permanent or fatal and must, at the very least, last 12 months. Disability claimants must meet or equal a listing (or be unable to work) to be considered disabled by the Social Security Administration. Children may also be determined disabled if they meet or equal a listing for children's impairments. All Supplemental Security Income and Social Security Disability Insurance applications are evaluated by the Disability Determination Services office to establish disability.