how to use cut tool (editable poly) with maxscript

Hi! I am new here and new to maxscript and I want to say that this is an excellent site :) and I am a big fan my problem is I want to use cut tool (editable poly with max script) but didn't succes following maxscript documentation the cut fuction have 4 arguments

polyOp.cutVert Poly poly int start_vert point3 destination point3 projdir

I didn't understand what is exactelly projdir

I want to developpe a script that is able to cut a polygonal surface converted from a spline I already write a script it work but not in all case in this one I used createEdge but I want to replace it by cut... here is the code

macroScript fixspolyspline_y category:"popa_3d"

(

on isEnabled return

selection.count == 1 and classof selection[1].baseobject == Editable_Poly

on execute do

(

obj = selection[1]

p= polyOp.getNumVerts obj

n=0
w=0
v=0
s=0
d=0

q=0
for i=1 to p do(
for j=1 to p do(

a = [n,w,v]
b = [q,s,d]

a= polyOp.getVert obj i
b= polyOp.getVert obj j

if a.y == b.y then(
obj.createEdge i j)
)

)
)
)

see the image to see what script do