US Military jargon: (acronym: DRU) An organization which does report through a normal hierarchy to a higher-level. For instance, the normal combat Air Force hierarchy is:

Headquarters, USAF
Major Command
Numbered Air Force

A squadron which reported directly to Numbered Air Force is one example of a DRU. AFOTEC, as a center (Wing-equivalent), reporting directly to Headquarters is also a DRU.