Precision

Patent attorneys should be cognizant of the degree of precision used in reciting numbers in claims. In patent law, claiming alkalinity of pH 10 is quite different from claiming alkalinity of pH 10.0. The former instance is usually taken to include a range of 9.5 to 10.5, while the latter is usually taken to include a range of only 9.95 to 10.05. The same applies to units of length, weight, and so forth.

On the other hand, it is understood that only realistic subsets of the permutations are contemplated. For example, U.S. patent no. 4851058 , claim 1 recites:

1. A magnetically hard alloy composition comprised of at least about 10 to about 40 atomic percent neodymium, praseodymium or mixtures thereof; at least about 50 to about 90 atomic percent iron and from about 0.5 to 10 atomic percent boron.

Obviously, it is impossible for all of the components to be present at the upper ends of the specified ranges, i.e., 40% neodymium, 90% iron, and 10 percent boron.