PROCEDURE decus$delete_null_lines
   LOCAL this_line, 
	 this_length,
	 this_buffer,
	 this_position;

   this_position := MARK (none);
   this_buffer := CURRENT_BUFFER;
   POSITION (BEGINNING_OF (this_buffer));
   loop
      exitif MARK (none) = END_OF (this_buffer);
      if LENGTH (CURRENT_LINE) = 0 then
         ERASE_LINE;
      endif;
      MOVE_VERTICAL(1);
   endloop;
   POSITION (this_position);
ENDPROCEDURE;