[From the aol.com Q-and-A session with RJ, 27 June, 1996]:

Question: Can gateways be created at non-right angles to the ground? If not, why not? If yes, why haven't we seen them?

RJ: They can be, and you haven't seen it because there's been no need to do it. And also some of the people who can make gateways don't know how to do it.