2.5.2 THE NECESSITY OF LOGICAL CONTINUITY

There apparently exists a very strongly held view among many members of NCOSE that requirements analysis is a proper precursor to functional analysis. This view was documented in MIL‐STD‐499B, which failed approval as DoD moved toward commercial standards in manufacturing and management areas, but lives on in draft IEEE P1220 and draft EIA 632. The author tried for several years prior to publication of his book System Requirements Analysis to arrange the elements of the system engineering process using this sequence, such that there existed a condition of logical continuity, without success. SAMSO and BMO system requirements analysis documents, such as SAMSO STD 77‐6, offered an alternative that encouraged logical continuity and that was the basis for the author's book, System Requirements Analysis . This paper makes the case for the necessity for logical continuity in the development of systems to satisfy complex needs, identifies a work sequence that complies, and exposes the discontinuity entailed in the approach encouraged by current standards. The author recognizes that the position expressed in this paper may be separated from the position endorsed in current draft standards only by semantic differences, but attempts to expose such differences have been unsuccessful to date leading to the conclusion that the differences are substantive. Those who hold the view opposed to that expressed in this paper are encouraged to contrast their position and carefully explain how their approach assures logical continuity or declare the lack of any need for it.