MIEventer: I am only a Novice level eventer. Although I am not at the most advanced eventing level, I have a green horse. Also I am booksmart (Pony Club), which is the whole reason I opened this thread in the first place. To share my knowledge from eventing and Pony Club, combined with the answers of others to help more people learn about eventing.
Spastic Dove (coffin canter): The coffin canter is very similar to the collected upbeat canter I was talking about with MIEventer. It is a collected canter used to help you approach and takeoff at the ditch in a coffin jump correctly. A coffin canter is important, because of the way a coffin jump is constructed- You need to stay calm, supple, and collected, in order to reach all three parts correctly and accurately.
Hope this helps! E