Read-only property that specifies the rails for the loft. If the LoftDefinition.LoftType is not kRegularLoft or kLoftWithRails then set this property will raise error, you should follow below rules to set this property:
If the LoftDefinition.LoftType returns kRegularLoft you can set this property directly.
If the LoftDefinition.LoftType returns kLoftWithCenterline you need to clear the LoftDefinition.Centerline before setting this property.
If the LoftDefinition.LoftType returns kLoftWithAreaGraphSections you need to clear the LoftDefinition.LoftSectionDimensions if any and LoftDefinition.Centerline before setting this property,