Each of the four exams (also referred to individually as Paper A, B, C, and D) is four hours in length. Paper A relates to the drafting of a patent application. Paper B relates to the validity of a patent. Paper C relates to the preparation of a response to an Official Action. Paper D relates to the infringement of a patent. Unlike the US system, the Canadian examination format is paper based with a variety of essay-type and short answer questions and is offered at least once a year, typically in April. Results are typically known within 5 months.