I gotta take a crap.

The best thing you can do is look at the toilet mfr.'s product data WELL IN ADVANCE, of doing wall layouts, plumbing rough ins etc., like was said, there are 10", 12" rough ins, rear discharge, and others. The product data for the toilet will provide dimensions. We would take the product data of what a contractor would propose to install, and review it against Arch., Mech. DWGS. On residential high rises, I can remember having close calls with elongated bowls and the door swing, the details of any room that is a lavatory, kitchen or anything with mechanicals always needs to be coordinated, architectural layout with the mechanical layout superimposed over it to determine conflicts, general rule of thumb, it's a lot worse when you have a few hundred units and something like this is overlooked !