Read newfeatures2002.txt...
But for sakes:
NPC Code:
showpoly index,{x1,y1,x2,y2,...}
It can keep going beyond one set of coordinates, and it will basicly draw a line to each coordinate in order and fill in any spaces with a solid color.
NPC Code:
showpoly 0{
playerx,playery,
playerx+2,playery,
playerx+2,playery+2,
playerx,playery+2
};