To avoid confusing one organization with another, the Air Force employs an identification system known as lineage. Although an organization that exists today may have begun its existence with a different name or a different number, or both, and may have existed for one or more periods only on paper, it can be identified as the same organization through its lineage. A basic policy of the Air Force is that each organization will have a unique lineage. Lineage is based both upon organizational status and organizational actions.
Several factors control organizational actions.
Among the most crucial determinants is whether an organization is a unit or an establishment. The squadron, on the other hand, has existed exclusively as the working level air unit since the designation of the 1st Aero Squadron in 1913. It includes the numbered flight, since flights are merely abbreviated squadrons. Finally, miscellaneous units, the third category of Air Force units, includes all units not covered in the headquarters and squadron categories, such as bands, hospitals, dispensaries, and schools. An establishment is an entity which consists of a headquarters, at group level or above, to which subordinate units can be assigned with attendant personnel, equipment and facilities.