Another window question - Screws along top/bottom(?)

Hey Gang,
OK, I've got a newbie question regarding these aluminum crank-out windows
They come with screw holes up and down the sides, but not across the top and bottom. Does this mean they only need the screws along the sides? I'm using butyl tape to seal them.
I also sent an email to Grant at L'il Bear, and I know he will provide me with an answer, but thought I'd go ahead and post the question here, too.
Thanks,
AL.
OK, I've got a newbie question regarding these aluminum crank-out windows

They come with screw holes up and down the sides, but not across the top and bottom. Does this mean they only need the screws along the sides? I'm using butyl tape to seal them.
I also sent an email to Grant at L'il Bear, and I know he will provide me with an answer, but thought I'd go ahead and post the question here, too.
Thanks,
AL.
