A sign for viewing by persons in a traffic area accessible by the random passage of persons through the area, the sign including a label formed of a thin layer of plastic material upon which the subject matter of the desired sign is printed. The spool braking device includes a rotating member, a brake shoe, a brake drum, and a selective fixing member. To be concrete, a plurality of mobile stations are classified into groups by a classification section 19, and an area to which each group moves is estimated by a directivity determination section 20.