Functional requirements are an especially important piece of the systems development lifecycle.
They specify behaviours of the system.
There are two mutually exclusive paradigms to follow on the formal definition of requirements, referred to here in an ad-hoc manner as function-centric and qualitative until better descriptors are found.
The qualitative school considers functional requirements to be feature specifications for the system, with non-functional requirements being counterparts to those functional requirements specifying implementation overrides that define how those functional requirements must be implemented, and also define behaviours related to the feature specified by the system or component being defined, such as quality attributes, including performance or other metrics.
The generally less popular function-centric school of thought considers functional requirements to be core feature specifications with non-functional requirements being additional feature specifications not defining to the core purpose of the system or component being designed.
SILO's system architectural lifecycle uses elements from both of these, in that it separates functional requirements into primary and secondary characteristics, using non-functional requirements to specify implementation overrides and behaviours related to behaviours of the system.
Pages in category "Functional Requirements"
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