[lisztfr9]

Ok, but why is it so confusing ?

because this is not RPN :

(o,g,"x x y - abs "+string(z)+"

The first "x" must belong to the syntax of the function, but seems also be a part of an RPN expression.

But for being RPN, it would need 2 operators behind, where there is only 1.

Also, there are 2 levels of quotes, around variables and around expressions ! The "abs" statement, applies to a parameter inside quotes, which usually enclose strings variables.

And finally, x y usually refer to coordinated along X and Y axis in a plan...