User Requirements vs. System Requirements
I’ve often run into debates over whether it’s worth distinguishing between user requirements and system requirements. I would argue that having precision around the perspective helps you make more effective trade-offs, as well as make sure you’re looking through the appropriate lens when you need to. In Scenarios, Stories, Use Cases: Through the Systems Development Life-Cycle, Ian F. Alexander and Neil Maden write about distinguishing between user requirements and system requirements.
User Requirements and System Requirements are Two Ends of the Spectrum
Alexander and Maden write that user requirements and system requirements are two ends of the spectrum:
Note that we have consciously differentiated User Requirements from System Requirements as in Mazza et al. (1994). This is viewed as a contentious issue by some: they maintain that the distinction between User and System requirements is spurious and that in reality there are just “requirements.” To be fair to this way of thinking, it is certainly true that requirements can at times be difficult to pigeonhole within the classification scheme. However, it seems equally obvious that there are two ends of the spectrum involved here, and that labeling the extreme points is a useful way of ensuring that a balanced requirements specification is produced.