major system
(5) The term “major system” means a combination of elements that will function together to produce the capabilities required to fulfill a mission need. The elements may include hardware, equipment, software or any combination thereof, but excludes construction or other improvements to real property. A system shall be considered a major system if (A) the conditions of section 2302d of this title are satisfied, or (B) the system is designated a “major system” by the head of the agency responsible for the system.