setDifference
Works with VSimEM, VSimPD, and VSimVE licenses.
Creates a CSG object that is the set difference of two CSG objects.
setDifference Parameters
- regions (string vector)
- List of regions to be combined. If this is not set then two STRgn blocks must be defined. 
- STRgnx (block)
- A region to be combined. 
Example setDifference Block
<STRgn PBGSlab>
  kind = setDifference
  <STRgn box>
    kind = box
    lowerBounds = [0.0  0.0  -0.5]
    upperBounds = [5.0  5.0   0.5]
  </STRgn>
  <STRgn holeArray>
    kind = array
    region = holeRow
    origin = [0.0  0.5  0.0]
    period = [0.0  1.0  0.0]
    numTranslations = 5
  </STRgn>
</STRgn>