Undocumented methods and properties in SMI Engine

Looking at the type library for SMIEngine, there are a number of methods and properties that aren't in the documentation. They look like they were introduced when version 5 motors were released.
Is the LanguageFile property of ISMIScan just the version of motor to validate to, or does it have to be pointed to an actual file with the information? Are the VT and V properties of ISMIMotor interchangable, or do I need to use the correct one depending on the version of motor I'm using?