def _create_dot(self, vd, parent, rock_ridge, xa, file_mode):
        # type: (headervd.PrimaryOrSupplementaryVD, dr.DirectoryRecord, str, bool, int) -> None
        '''
        An internal method to create a new 'dot' Directory Record.

        Parameters:
         vd - The volume descriptor to attach the 'dot' Directory Record to.
         parent - The parent Directory Record for new Directory Record.
         rock_ridge - The Rock Ridge version to use for this entry (if any).
         xa - Whether this Directory Record should have extended attributes.
         file_mode - The mode to assign to the dot directory (only applies to Rock Ridge).
        Returns:
         Nothing.
        '''
        dot = dr.DirectoryRecord()
        dot.new_dot(vd, parent, vd.sequence_number(), rock_ridge,
                    vd.logical_block_size(), xa, file_mode)
        self._add_child_to_dr(dot, vd.logical_block_size())
An internal method to create a new 'dot' Directory Record.

        Parameters:
         vd - The volume descriptor to attach the 'dot' Directory Record to.
         parent - The parent Directory Record for new Directory Record.
         rock_ridge - The Rock Ridge version to use for this entry (if any).
         xa - Whether this Directory Record should have extended attributes.
         file_mode - The mode to assign to the dot directory (only applies to Rock Ridge).
        Returns:
         Nothing.