Thanks! What I still don't understand though is how an equation that uses a vector quantity with three distinct numerical components (nurbsPlane1ParticleShape.position) can yield a single decimal numerical value (float $nz).
If, for example, nurbsPlane1ParticleShape.position is equal to <<2,3,4>> and that value is then inserted into the equation, then shouldn't the equation also yield a vector quantity?
ps. Nice Quake III model btw.