A printing-machine form cylinder having, in an interior space thereof, a winding reel and an unwinding reel for a printing film drawn around the outer casing surface of the form cylinder, respective ends of the printing film being fastened to the winding reel and the unwinding reel inside the form...http://www.google.com/patents/US5809881?utm_source=gb-gplus-sharePatent US5809881 - Form cylinder having a gap closed by a cover element having a roller mounted thereon 
