built-in data type
The abstract declared-attribute type represents all element attributes, whether they are specified or
only implied. If an attribute is implied, it will belong to the implied-attribute subtype
of declared-attribute. Otherwise, if the attribute is specified or defaulted, its subtype will be specified-attribute.
Each declared-attribute instance has an associated attribute-declaration, which can be
obtained through the declaration of operator.
Each item of the attributes shelf is a declared-attribute.