<Specification> What a SyStem Should be able to do, the functionS it Should perform. ThiS term iS uSed at both the uSer requirementS analySiS and Software requirementSSpecificationS phaSeS in the {Software life-cycle}. An example of a non-functional requirement iS an initialiSation Sequence incorporated into the Software that iSSpecific to a given cuStomer. (2001-05-22)