I booked our two tickets on Trenitalia, Roma to Venezia, and ed our seats. On the printout each side by side seat number had "detached window" in parentheses. What is a detached window?
The first-class cars on Italian high speed trains have 2 seats on one side of the aisle, one seat on the other. The "detached window" seat is the one on the single-seat side. It is "detached," and it has a window. You can see a picture here: http://tinyurl.com/bm2y982