Abstract. Traditional system engineering has been the source of most of the requirements' decomposition and management techniques. Requirements' decom-position and flow down concentrate on a top-down mission oriented view. The emphasis is on functional flow (input/output), black box performance allocation, and system interaction. However, it is weak in areas like operating logic, behavior, and timeline requirements.We contrast and compare the requirements' process and management techniques for the traditional system engineering and modern software approaches. We can indicate at least one gap in the area of operating logic and timeline analysis as well as numerous important under laps.Consequently, the design of many computer-based systems suffers from a substantial risk at the interface between system and software design engineering. The gap, created by a failure to address operational logic, sequencing, performance and timeline requirements in both disciplines, can have a major impact on program cost, schedule, and performance. Potentially, major safety related risks may result from the gap in logic and timeline requirements' tracking and allocation. In addition, significant under laps occur in operational analysis, interface control, performance, human factors, risk analysis, trade-off studies, reviews, and planning. Therefore, these can create a risk if the software engineering effort is weak in traditional system engineering discipline. Suggestions for reducing the gap and under lap are offered.