Any aspect of an Entity (but not a part of it), which cannot exist without that Entity. For example, the way the surface of a specific PhysicalObject looks like, or the specific light of a place at a certain time, are examples of Quality, while the encoding of a Quality into e.g. a PhysicalAttribute should be modeled as a Region. From the design viewpoint, the Quality-Region distinction is useful only when individual aspects of an Entity are considered in a domain of discourse. For example, in an automotive context, it would be irrelevant to consider the aspects of car windows for a specific car, unless the factory wants to check a specific window against design parameters (anomaly detection). On the other hand, in an antiques context, the individual aspects for a specific piece of furniture are a major focus of attention, and may constitute the actual added value, because the design parameters for old furniture are often not fixed, and may not be viewed as 'anomalies'.