@TechReport{	  hilty.ea:enforcement:2006,
  author	= {M. Hilty and A. Pretschner and C. Schaefer and T. Walter},
  institution	= {DoCoMo Euro-Labs},
  language	= {USenglish},
  month		= 2006,
  number	= {I-ST-018},
  title		= {Enforcement for Usage Control--An overview of Control
		  Mechanisms},
  year		= 2006,
  user		= {pretscha}
}