In Canada, every patent application must include the “specification”. The patent specification has three parts: the disclosure, the claims, and the abstract. The contents of the specification are crucial in patent litigation. Components of the specification Disclosure requirements The requirements of disclosure are set out in s. 27 of the Patent Act: In the disclosure, the applicant explains what his or her invention is and how to put it to use. For a product, this means that the disclosure must show how to make and use the invention. For a new combination, the elements of and result of the combination must be detailed. For a machine, the inventor must indicate the principle of the invention and the best mode of applying it. The sufficiency of the disclosure, with any valid amendments made to it, is judged at the patent's claim date. The disclosure must be fair, honest, open and sufficient. If a person skilled in the art can arrive at the same results only through chance or further long experiments, the disclosure is insufficient and the patent is void. The disclosure must give skilled readers enough information for them to easily use the invention when the patent expires, and for them to try to improve on or experiment with it in the meanwhile. Thus, a patent holder who holds back essential information invalidates the whole patent. The disclosure would also be insufficient if it is simply wrong and a person skilled in the art cannot use the disclosure or her general ability to replicate the invention. If a person skilled in the art would readily spot the mistake or omission and quickly correct it by using common general knowledge and the rest of the patent, but without "prolonged research, inquiry or experiment" or inventiveness, then this will not invalidate a patent. Best mode As part of their duty of full disclosure and good faith, inventors must reveal their best mode, or "preferred embodiment", of using the invention, even if that mode is not claimed in the patent application. The mode must be the best one the inventor knows at the claim date, and must be well enough disclosed for other skilled workers to practice it without undue experiment. When read literally, the Act provides a best mode duty only for machines (see above Patent Act at s 27(3)(c)). This led one court to recently confine the doctrine to machines while