If it's analogous to 3D space + 1D time = 4D, then it's not a question of specifying one or the other, and then a location in the one you've specified. Each point will have a location in both of the 2D spaces - that is, 4 coordinates, which does amount to a 4D space.
I'm not saying I really understand it, mind you.
I'm not saying I really understand it, mind you.