A simple attribute may have any value from a particular primitive domain. If the value is restricted to a single primitive, the allowed value is given using this subclass.
Note that this subclass is also used to define restrictions as related to the use of enumerations. In this case, the attributeName is provided in double-quotes (without explicitly stating .description or .value) and the attributeValue is the allowed description in double-quotes. For example, if the enumeration is Color and the choices are blue, green and red, a restriction may be defined by specifying attributeValue as green in double-quotes.
RestrictedDomain may be used by a restricted clause or as the means for expressing defaults and class attribute values, as indicated in TupleDefinition.