Particular attention is required whenever the word "about" or similar terms such as "approximately" are used. Such a word may be applied, for example, to a particular value (e.g. "about 200 C") or to a range (e.g. "about x to about y"). In each case, the examiner should use his judgment as to whether the meaning is sufficiently clear in the context of the application read as a whole. However, the word can only be permitted if its presence does not prevent the invention from being unambiguously distinguished from the prior art with respect to novelty and inventive step.