As software projects are getting more and more complicated, the greatest risks in software engineering are most probably emanating from the limitations of an inexperienced developer in imagining the boundaries of an abstract artefact that does not even exist yet. Requirement engineering is extremely important in a software development project, yet inherently difficult. Requirements can be redundant, optional, overlapping and even contradictory. They come from different sources and often are represented in an informal way. Requirements also are followed throughout the development process and can be partially met in different degrees in various stages of the process. In this work we advocate a fuzzy logical model for following the requirements and their fulfillment. We also present the logical design of a requirements knowledge base manager that we are building in order to facilitate requirement-aware rapid development tools.