I'm guessing you really want to know more about the MFS 700?
First, search for "MFS Notes" a document assemble by Ned Young. I just glanced through it and didn't see the dimensions you want but maybe they are there.
Since the end of a rail (short or long) always butts into the side of another rail, and the rails of same length are mounted in opposite directions, the overall size of the MFS depends on what size aperture the rails are set to. The largest possible aperture yields the smallest overall area. At the smallest aperture the rails are extending out in opposite directions so the overall area is almost doubled. To get the overall size (at largest aperture) of the short side of an MFS you add the width of a rail to the length of the short rail. To get the size of the long side you do the same with the long side. To get the overall size (at smallest aperture) of the short side of an MFS you simply add the length of 2 of the short rails together. To get the size of the long side you do the same with the long side.
Unfortunately, in my quick perusal of the Notes I didn't see any of the dimensions you need. The only rail dimension I found is the thickness, 16mm. I'm not even sure if 700mm is the actual length of the long rail or the net capacity of the long rail.
So,
short side = rail width (?) + short rail length (?)
long side = rail width (same as above) + long rail length (?)
Anyone know those dimensions?