(225 ILCS 705/33.06) (from Ch. 96 1/2, par. 3306)
    Sec. 33.06. A separate map shall be made of the surface whenever the surface buildings, lines or objects are so numerous as to obscure the details of the mine workings if drawn upon the same sheet with them, and in such case the surface map shall be drawn on transparent cloth or paper so that it can be laid upon the map of underground workings and thus indicate the relation of lines and objects on the surface to the excavations of the mine.
(Source: Laws 1953, p. 701.)