# File proofreader.rb, line 172
    def closure?(element, die=nil)
      die = @proofsheet.die(element.inherited_namespace, element.absolute_xpath) if not die
      validity = true  # default unordered, so valid
      if die
        if die.closure and element.has_elements?
          closure_how = die.closure[0]
          closure_has = die.closure[1]
          # load childern element tag names into an array
          children = []
          element.elements.each do |child_element|
            children << child_element.name
          end
          case closure_how
          when 'inclusive'
            diff = closure_has - children
            if not diff.empty?
              validity = false
              error = "CLOSURE inclusive"
              @errors << [die.namespace, die.xpath, error]
            end
          when 'exclusive'
            diff = closure_has - children
            if not diff.empty?
              validity = false
              error = "CLOSURE exclusive"
              @errors << [die.namespace, die.xpath, error]
            end
            diff = children - closure_has
            if not diff.empty?
              validity = false
              error = "CLOSURE exclusive"
              @errors << [die.namespace, die.xpath, error]
            end
          end
        end
      end
    end