Ribbon Boards and Strongbacks
Strongbacks - A strongback helps to distribute the loads on a floor truss, thereby helping reduce the "bounce" the floor system might otherwise have. Strongbacks are typically specified every 10' across the floor truss. As you can see in the images below, a strongback has been attached to the verticals of the longer floor truss.
Ribbon Notches - Floor truss ends can have a notch built into the top of the truss. The purpose of these notches is to help the framer line up the trusses and to help support the subfloor around the perimeter. By putting a 2x4 board at the end of the first few trusses, the remaining trusses can easily be slid into place when they hit the ribbon board.