Big-displays three frames: the left frame window, the top window (with tracking links), and the main topic window.
Small-displays three frames, as with the Big Screen selection, but the frames are smaller.
No Frame-displays the top window (with tracking links) and the main topic window only.
Accessible-displays the top window (with tracking links) and the main topic window, as with No Frames, but enables the user to use keystroke combinations to perform tasks instead of using the mouse.