27] Phostech’s argument with respect to claim 3 of the ‘115 Patent is a classic lawyer’s argument, namely that where a draftsman (or patent agent) uses different words, different meanings are intended. Counsel for Phostech put before us a table showing the various expressions used in the patent such as “ source of [element]”, “[element]-containing compound”, “[element] compound”, the point of which was to underline that the drafters of the patent referred only to “carbon” and did not include the qualifying words used in relation to other substances. From this, Phostech argued that where the patent refers to carbon, it means carbon in a pure form as opposed to some other compound which may be a source of carbon.
 The fact that a lawyer, using the usual rules of interpretation, might come to a different conclusion, is of no consequence. The patent is not directed to lawyers but to persons skilled in the art. This principle is anchored in the language of the Patent Act itself (R.S.C. 1985, c. P-4, s. 27(3)(b) [emphasis added])