American patent laws are radically different and more backwards in common sense than ones say in India. In India you can patent only a process/means how to do certain thing, not a thing itself, what is more natural, and this is a main dispute between american industry and various movements in India. For example, once there is a nuclear energy, one can use it for any thing which requires energy. But in american law it is theoretically possible that in times when there was not a single nuclear submarine, one registers a patent for the idea/concept nuclear submarine without any specific techincal details on construction. Similarly for the concept of a shoe which charges battery by using the energy disssipated in changing pressure on the shoe when walking. In Indian patent law, any specific way to achieve that is patentable. But somebody else who wishes to independently makes another design achieving the same function can not be prevented by that patent. Also in Indian patent law one can not patent existing natural resources, like species of wild plants, naturally existing compounds in plants na rocks and alike; and my understanding is that this hence applies to mathematical facts like number 13 is prime even if before unknown to the mankind. Zoran [For admin and other information see: http://www.mta.ca/~cat-dist/ ]