In many inventions relating to telecommunications or computers, the underlying novel idea resides in the modification of a signal to achieve some useful purpose. An example can be found in US patent application 09/211,928, which relates to the introduction of watermarks into signals to help protect media against unauthorized copying. Consistent with the general desirability of protecting an invention in its most basic form without limitation to any specific apparatus or method of implementation, the applicants sought to protect their underlying invention in the form of a claim directed to a signal, wherein the body of the claim defined the novel and useful characteristics of the signal. The US Federal Circuit (In re Nuijten, 84 USPQ 2d 1495), with a dissenting opinion, held that such a claim was not a "process, machine, manufacture, or composition of matter", as required by US law, and as such was non-statutory subject matter.
