attr_dcl : [ 'indexable' ] 'attribute' type_spec declarators
An attr_dcl defines one or more attributes of the enclosing interface. The attribute names defined by the attr_dcl are the IDs appearing in the declarators. The type of each attribute is the type that would have been bound to the name if the keyword attribute were replaced by typedef. If the type_spec is a constructed_type, the attr_dcl is equivalent to a type_dcl followed by a attr_dcl; that is,
attributeS D;where S is a constructed_type, is equivalent to
S;where N is the type defined by S. The word indexable indicates that this attribute may be used in the indexed_by clause of a relationship (see the next section).attribute N D;