In a manner quite similar to the requirements categories introduced in section 1.15 goal categories establish a distinction between functional and non-functional goals together with their respective specializations:
- A Functional Goal states the intent underpinning a system service, for example schedule convenient meetings, control acceleration of trains for rapid transportation.
- A non-functional goal states a quality or constraint on service provision or development, for example minimum interaction with participants during meeting scheduling, safe distance maintained between trains.
7.5 shows a goal taxonomy corresponding to the requirements taxonomy discussed in Section 1.1.5 (see Figure 1.5):