As for "non-functional requirements" ("NFRs") Wikipedia suggests examples: 1. Execution qualities, such as safety, security and usability, which are observable

As for "non-functional requirements" ("NFRs") Wikipedia suggests examples: 1. Execution qualities, such as safety, security and usability, which are observable during operation (at run time). 2. Evolution qualities, such as testability, maintainability, extensibility and scalability, which are embodied in the static structure of the system.[5][6] Sometimes "the business side" has the expertise required to define these. Sometimes they don't, and engineers need to do it, using whatever knowledge of the business they have. "The business side" often will not take responsibility if the system is insufficiently testable, maintainable, extensible, scalable, secure, or usable, instead blaming engineering.