All wedding dresses with a train will have thumb hook to help you carry the train as you walk.  It's always located on the underside of the train in the center about a foot from the edge (usually a 6 inch satin ribbon loop).  Some brides never notice it, and others try to cut it off thinking it's just a hanger hook (which it can be used for that as well).  It's a great way to easily get around in your dress without having to fully bustle it.