ProductSpecifications also have a variety of characteristics, such as a printer’s dimensions, paper capacity, print speed, color, and so forth, and possible values associated with the characteristics.  The SID uses ProductSpecification Characteristic and ProductSpecCharacteristicValue to represent the properties for a ProductSpecification [Fowler-Properties] as shown in Figure Pr.4 on the following page.  Additional information regarding this pattern can be found in Common Domain guide book section Root Business Entities ABE.<br/>Characteristics can be grouped into four different types:<br/>        • If a characteristic has a discrete value (e.g. color or business coding), it may be derived from a range of allowable values;  <br/>        • If a characteristic describes the product within a parameter range  (e.g. dimension), it may be defined with a ‘high value’ and a ‘low value’ [Fowler-Range] ;  <br/>        • If a characteristic value is ‘derived’, it will use other parameters in a formula.  N.B.  There are business rules implied here that require more work in a future phase of the SID Product definition.<br/>        • If a characteristic has no predefined values and unconstrained values (no business rules and no ranges/allowed values)<br/>Characteristics can also be bundled together into packages by using the ProductSpecCharRelationship.  For example, a number of electrical characteristics can be grouped together using an “electrical properties” characteristic that represents a composite of the detailed properties, such as power requirements, plug requirements, and so forth.  This entity can also be used for a number of other relationships between characteristics, such as mutually exclusive, inclusive, and so forth.<br/>CharacteristicValues can reference other CharacteristicValues.<br/>As ProductSpecifications are upgraded, and as the market and technology move on, they are subject to version control.  If there is a significant change of capabilities, a new ProductSpecification is created.<br/>When a product is created based on a ProductSpecification (see Product Offering below), the party may also have the option to choose from a set of properties values, such as color, or may be able to choose one from a number of product properties.  Where a ProductSpecificationCharacteristic is interchangeable with others in this way, it is modeled as a ConfigurableProductSpecificationCharacteristic. <br/>