Categorising Surfaces with Reference to a Plane **UPDATE**

**UPDATE** The solution has been modified to allow for inverted level surfaces

Here is an example of how to categorise surfaces according to a reference plane. Written for version 0.8.0061

3 groups: Sloping Down, Level and Sloping Up

Level is defined by a +/- tolerance

Inputs:

Srf: List of surfaces

Pln: Reference Plane

Num: Tolerance

Outputs:

Srfs {0} 

Srfs {1}

Srfs {2}

Please post any suggestions for alternatives.