Multi track steel doors glide outwards into the outriggers giving full opening, without the need for the doors to cross. Tailgate is an optional extra.
Pros and Cons:
If you need to have full width open at any time, and if you have apron space either side for the door tracks, then outrigger doors are the best. They open one way. It is possible to have a tailgate, but this is best avoided if you can have full height, full width doors.