If I'm not mistaken--and we'd have to check this--I believe that is actually language in the statute. I think it simply recognizes the fact, and this is from a regulatory point of view, so perhaps this question would be better directed toward Transport Canada.... I suspect that very subtle changes in something could, at least from a point of view of perception, change degrees or shades of this or that. Essentially I believe that's statutory language. It's not Nav Canada's language. I believe it's guidance for the safety regulations.
On March 3rd, 2009. See this statement in context.