Public Function AddVariable( _
   ByVal NumberOfEdgeSets As Long, _
   ByRef EdgeSetArray() As Object, _
   ByVal NumberOfVertices As Long, _
   ByRef VertexArray() As Object, _
   ByRef VertexRadiusArray() As Double, _
   Optional ByVal RollAcrossTangentEdges As Variant, _
   Optional ByVal RollOrCapAcrossSharpEdges As Variant, _
   Optional ByVal RollAlongBlendEdges As Variant, _
   Optional ByVal ApplyVertexBlends As Variant _
) As Blend