SKurj is right.
Scissors is a simple form when in horizontal, but any "situation where the paths of the two planes going in the same direction cross each other" can be considered "scissors". This means scissors can be used in all sorts of directions - while going forward, while turning, while diving, while zoom climbing... etc etc.
The ultimate form of the scissors is the "Rolling Scissors" - the move Skurj described.
Two planes enter a move simular to the barrel roll, but the two planes are about "half tempo" different in flight path and thus, they go in a move resembling a double helix.. when observing the rolling scissors with the film viewer, you'll notice the trails look like a DNA code. The two planes enter a double helix flight path, each trying to overshoot the other, each rolling in a wide arc to move away from the other's gun solution.
There is no way this can be described with just words, so I'll try and find a good film or a pic for you.