I'll give you an idea of the process. An applicant files in Canada and applications are laid open 18 months after. So the information on the invention is open to the public. But at that time the patent is pending, so there's some uncertainty as to whether or not it's going to end up as a patent. Eventually for a firm to use the information and develop further, there's some kind of a risk there, because if it eventually becomes a patent...you don't know.
What happens is that applicants, as Sylvain mentioned before, have up to five years to request examination, so the application that is pending is eventually examined by the patent examiners to determine whether it complies with the requirements of the Patent Act. This process depends—because it's an intuitive process in the sense that sometimes an application can be allowed and granted eventually when it's examined the first time. But there can be many multiple iterations between the patent examiners and the applicant to determine the scope and whether or not it meets the requirements of the act. During that period of time, companies interested in the invention may keep an eye on the invention and the evolution, but if they use it, there's always a risk, up until they know for sure whether it's a patent or the application is abandoned or not granted to the applicants.
I hope this answers your question.