Drick,
Hate to see that one's been hangin' out here for a little bit with no responses, but it might be the phrasing of the question ... at least it left me a little puzzled ... not sure if I exactly understand, but the dados themselves can run either horizontaly (to support a shelf for instance) or verticaly (i.e., to hold a divider in place) - a dado is simply a slot or grove that's cut into one piece of wood to accept another piece and form a joint, and as such, can run either direction as well as on an angle (wine rack for instance). If that missed the jist of your question, come on back and clarify a little.