A-Spec

A type of specification covering an entire complex system, or a major portion of one. As far as I can tell, the term appears to have originated with MIL-STD-490. A good statement of purpose is in DI-CMAN-80008: the A-spec was used to define and partition the requirements allocable to all or part of a system…

“(1) assigned to different contractors or government organizations directly responsible to the contracting agency for that part of the system’ total performance, (2) added on a evolutionary or incremental basis, or (3) planned for major modification.

DI-CMAN-80008 was superseded by DI-IPSC-81431 (now at revision A) but the current DID does less to explain the purpose than did the original DID1.

Footnotes
  1. It also has fewer teeth, e.g. “…The distinction between states and modes is arbitrary. A system may be described in terms of states only, modes only, states within modes, modes within states, or any other scheme that is useful…”.[]