The keystone of ISO work is that the basis of an evaluation is an explicit and detailed statement of what is required of the object to be evaluated. This statement is formulated very early in the process of defining an evaluation and is called a “quality model”. According to Zhu et al [18], the following requirements must be identified on representation of quality models, (a) A quality model should explicitly associate quality attributes or quality carrying properties to the components of the system, (b) A quality model should associate abstract properties with observable and verifiable phenomena of the component or system and (c) A quality model should be able to present the rationale of the relationships between properties, such rationales can be system specific and should be able to be verified and validated in the context of the system.