During model-based documentation of requirements in requirements engineering, three types of requirements are documented independently and used in conjunction:
Goals describe intentions of stakeholders or groups of stakeholders. Goals can potentially conflict with one another.
Use cases and scenarios document exemplary sequences of system usage. Scenarios are grouped together in use cases.
System requirements (generally referred to as requirements) describe detailed functions and qualities that the system to be developed shall implement or possess. In addition, system requirements provide complete and precise information to serve as input for subsequent development steps.
In practice, requirements ...