operator
declaration of (element-expression | entity-event | declared-attribute)
 The operator declaration of returns
        the element-declaration, entity-declaration, or
        attribute-declaration of the element-expression, entity-event,
        or declared-attribute, respectively, that it is applied to.
      
 In the case of an SGML or validating XML parse, an element-declaration can be obtained in an
        element rule with declaration of #current-markup-event. In a well-formed XML parse,
        this returns a declaration that contains the element's name and nothing else. In a markup-parse,
        it returns the original declaration of the element. The same expression used inside
        an external-text-entity rule returns an entity-declaration instead.
      
 An expression like declaration of attribute "a" can be used to obtain the
        attribute-declaration of the attribute in question. Inside an element rule, this expression would
        be equivalent to (attributes of declaration of #current-markup-event){"a"}.