Page with a green mark at “Functional requirements”… Text from the page:
Requirements can be classified into several categories [33]:
Functional Requirements specify what a system must do, defining its behavior
in response to specific inputs, events, or conditions [23]. E.g.,: “The system
shall authenticate users before granting access.”
Requirements protect systems from accidental harm by preventing
hazardous behaviors, detecting safety violations, and ensuring appropriate
responses to unsafe conditions. E.g.,;: “An autonomous vehicle shall never
exceed the posted speed limit” [24].
Performance Requirements define measurable criteria for system quality
attributes including speed, throughput, reliability, accuracy, and resource uti-
lization [7]. E.g.: “The system shall process transactions within 2s.”
These categories represent common requirement types, though many others
exist (e.g., security, usability, maintainability requirements).