animation paper has to sit on a peg bar to line up each frame, and while you animate , you have to flick between the drawings to see how your animation looks.
if you put your paper on top pegs you can only flip when you stop and grab the stack and let the papers fall.
if you peg on the bottom, you can hold up to 5 pages in between your fingers and roll the pages as you draw and animate so you can make adjustments faster :3