In the 1970s, Tom Demarco believed that we should spend a significant amount of time developing a description of the "current system". This meshed well with the development of Information Systems in accordance with DoD Standard 7935A.
About 2000, Tom Demarco revisited his Structured Systems Analysis methodology and stated that nobody would devote that much time to developing a description of something that needed to be replaced. Countries which could afford a significant defense budget could make faster progress using prototyping. A rich country such as the United States of America could fund thousands of engineers doing fun stuff. Even rich countries had problems funding all their engineers during cyclical economic downturns. The United States of America had a surplus of scientific and engineering professionals during the 1969-71 RETRENCHMENT.
Demarco was right in the late 1970s when information systems science was getting started and he was right about 2000 when Information Systems Engineering was going strong.
MIL-STD 490 A established the format and contents of
specifications for program–peculiar configuration items,
processes, and materials~. It was published on June 4, 1985. It superseded the previous edition of 30 October 1968.
When a change in scale is involved, it is likely not to be noticed unless one spends a significant amount of time on the current system description. Several changes of scale were involved in developing the System Description for the World-Wide Military Command and Control System (WWMCCS) [pronounced WIMEX].
The WWMCCS accomplished 6 Operational Tasks..These exist in the JCS requirements statement. In general, they accomplish the "military operational process" (sense, analyze, decide, act, communicate) which has been documented in various places. My earliest reference is AD0479368 "Concepts for Command and Control Systems",by Henry M. Parsons and William E. Perry, 23 December 1965.
The sense function included Tactical Warning. One of the first systems to support this function was SAGE.
The Semi-Automatic Ground Environment (SAGE) was a system of large computers and associated networking equipment that coordinated data from many radar sites and processed it to produce a single unified image of the airspace over a wide area. SAGE directed and controlled the NORAD response to a Soviet air attack, operating in this role from the late 1950s into the 1980s. Its enormous computers and huge displays remain a part of cold war lore, and a common prop in movies such as Dr. Strangelove and Colossus.
The command center displays were upgraded http://www.dtic.mil/dtic/tr/fulltext/u2/a242965.pdf is from the TRW Technology Series and describes this upgrade.
The WWMCCS included separate processes for "conventional" and "nuclear" planning and execution.
The WWMCCS Information System (WIS) was supposed to support the "Warfighters" in the National Military Command System (NMCS) and their command subordinates.
The Massachusetts Mafia won the WIS development contract but could not deliver. The Global Command and Control System (GCCS) was an effort to meet the needs of the NCA and the Warfighters.