# File htree/leaf.rb, line 25
    def initialize(root_element_name, public_identifier=nil, system_identifier=nil)
      init_raw_string
      if public_identifier && /\A[ \x0d\x0aa-zA-Z0-9\-'()+,.\/:=?;!*\#@$_%]*\z/ !~ public_identifier
        raise HTree::Error, "invalid public identifier in document type declaration: #{public_identifier.inspect}"
      end
      if system_identifier && /"/ =~ system_identifier && /'/ =~ system_identifier
        raise HTree::Error, "invalid system identifier in document type declaration: #{system_identifier.inspect}"
      end

      @root_element_name = root_element_name
      @public_identifier = public_identifier
      @system_identifier = system_identifier
    end