USAF groups may be dependent or independent: "A dependent group is a mission, maintenance, mission support, medical, or large functional unit (e.g., security forces, special tactics, communications, etc.) that encompasses a number of related squadrons to provide the specified capability to a parent wing. Such groups may possess small supporting staff elements, such as standardization and evaluation or quality control, that are organized as sections." "An independent group has the same functions and responsibilities as a like-type wing but its scope and size do not warrant wing-level designation and associated overhead costs." A group requires at least 400 personnel, while a wing requires at least 1,000. A fighter wing, for example, is normally composed of dependent groups: an operations group of typically three flying squadrons and an operations support squadron and a maintenance group with aircraft, equipment, and component maintenance squadrons and a maintenance support squadron.