I have not yet tried what happens with the code you have shown, but from what i see here :-

M0,0 v0.8 h1 v-0.8 z (example is anti clockwise)

M0,0 Moveto co-ordinates 0,0
v0.8 Cut 0.8 vertically
h1 Cut 1 horizontally
v-0.8 Cut -0.8 vertically (- means up)
z Cut to start (closes)

for a rectangle you would need v and h + a z to close