A requirement is simply a statement of what the system must do or what characteristics it needs to have. Requirements written from the perspective of user and focus on user needs are called __(71)__. Requirements written from the developer's perspective and describe how the system will be implemented are called __(72)__. Requirements evolve from detailed statemens of business capabilities that a system should have to detailed statements of the technical way in whick the capabilities will be implemented in the new system. Requirements can be either functional or nofunctional in nature. For example, during the analysis phase of travel vehicles sales system, the system that must have the ability to search for available inventory is __(73)__. The requirement that the system should be able to work on any Web browser belongs to __(74)__. That customer personal information is protected in compliance with the Data Protection Act is a requirement of __(75)__.
（73）应选？
