def extended(self) -> ListP:
        """The body structure attributes with extension data."""
        return ListP([String.build(self.maintype), String.build(self.subtype),
                      _ParamsList(self.content_type_params),
                      String.build(self.content_id),
                      String.build(self.content_description),
                      String.build(self.content_transfer_encoding,
                                   fallback=b'7BIT'),
                      Number(self.size),
                      String.build(self.body_md5),
                      String.build(self.content_disposition),
                      String.build(self.content_language),
                      String.build(self.content_location)])
The body structure attributes with extension data.