Hi MO;
I am sure I need to provide a drawing or photo to fully explain a five sided ridge, but I do not have time to post one right now.
I am talking about frames which have a ridge beam, not a ridge board, into which the tops of the rafters are tenoned and pegged. The essential timber framer's joinery reference book Historic American Timber Joinery gives a discription on page 38.
There certainly are an amazing number of variations of how historic timber frames were built!
Jim