| http://www.w3.org/ns/prov#value | - atching of relatively hard materials such as glass and plastic which generatecharacteristic sound or vibration frequencies during scratching, and for detecting and reporting the cutting and slashing of relatively soft materials such as fabric, leather and plastic.U.S. Pat. No. 6,064,309 dated May 16, 2000 and issued Sellers, et al. describes a swimming pool drowning prevention safety system.
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