ABSTRACT
Operational, functional, or design characteristic or constraint. There are many different kinds of require-
ment, giving rise to different kinds of language, analy-
sis, modeling, process, and solution. Note that this
definition has carefully avoided the term “non-
functional,” since there is a heated debate about what
this actually means. Design characteristics cover per-
formance, usability, safety, maintainability, and a host
of other qualities.
