This is an industry-standard approach to prioritizing project requirements. Each requirement is assigned to one of the following four categories: Must Have, Should Have, Could Have, and Won't Have (this time). Identifying the Must Haves helps the project focus on delivering the most important requirements, and the decreasing levels of priority with Should and Could Haves build in contingency to the overall delivery timetable. Won’t Have (this time) is useful both for clarifying project scope and for capturing intentions for possible future project phases. For more information on how KDL uses MoSCoW see our Software Development Life Cycle for Research Software Engineering wiki.