I've had a bit of a trawl of the Internet. Yamaha offer a service for issuing a Letter of Conformity for road motorbikes, so I guess they do the same for their outboards. There is a fee ofcourse! You would think that there was a standard document applicable to the motor or range of motors, I am sure this must be the case.

I am afraid I think you are going to have to contact them. If I remember I will dig out my papers for my motor tomorrow and have a look.

Jonathan