The rest of this document will focus on the actual design and operation of the PBAS. It will go over product perspectives and expected functions, characteristics and assumptions regarding the system, users, and environment, constraints on the system, sources of uncertainty that might confound expected operation, and external dependencies of the system. Then, it will define specific functional and non-functional requirements, before moving on to a review and discussion of security concerns. Finally, use case, domain, and goal models will be provided.