551 of title 5, United States Code. (3) Applicable rule The term applicable rule means a rule that may negatively affect, directly or indirectly, the health of a substantial number of children. (4) Child The term child means a human from the moment immediately after birth up to an age of 18 years. (5) Children’s representative The term children’s representative — (A) means a nonprofit organization or a municipal, State, or Federal agency, or Federal advisory committee that has the mission of protecting all children’s health and welfare or providing healthcare services to all children despite race, ethnicity, socioeconomic class, sexual orientation, or other identification markers