Holds a reference McFeatures for the parent McFeatures

This operator is exposed as McRegions.Reference, McLines.Reference and McPoints.Reference. It can also (and often will) be created independently using McEngine.CreateOperator, but it must have an McFeatures object (McPoints, McLines or McRegions) as its parent. The McRefFeatures.Duplicate method automatically creates a new object with the same parent.

The usual use for this object is to make measurements that depend on the relationship between the parent McFeatures and the ReferenceFeature.