Attributes common to all elements that function as accessors or represent independent (multi-ref) values. The ref attribute is intended to be used in a manner like CONREF. That is, the element content should be empty iff the ref attribute appears A list type that allows * and non negative integers. Used as the base type for arraySize below. Pattern based restriction of the arraySizeBase list type. Used as the type of the arraySize attribute. Restricts asterisk ( * ) to first list item only. Instances must contain at least an asterisk ( * ) or a nonNegativeInteger. May contain other nonNegativeIntegers as subsequent list items. Valid instances include; * 1 * 2 2 2 * 2 0