I am trying to draw a square with coordinates (-1,-1), (1,-1), (-1,-1) and (1,1). I thought i can use VREF = -1 1 and HREF= -1 1. But these give me extra lines that I do not need. Basically, i will like to know how to draw a horizontal line passing through Y=1, beggining at X=-1 and ending at X=1. Or how can I draw a verical line passing through X=1, beggining at Y=-1 and ending at Y=1.