2A dual Motor Controller problems

I have the 2a dual motor controller (http://www.dfrobot.com/index.php?route= ... duct_id=66), but it seems to be lacking in documentation. I have the l298n motor driver document, but that just seems to be the chip itself and not the entire board. แทงบอลออนไลน์มือถือ

What is the purpose of the jumper and the Vd, GND, Vs terminals? Vd = logic voltage, Vs = motor voltage?