Returns the version of the PropertyObject object if it is a root type definition.
If the object is not a root type definition, the property reports an error. Call IsRootTypeDefinition before accessing this property. The version string is in a format similar to that of DLLs and executables: "M[.m[.r[.b]]]," where M=major version, m=minor version, r=revision, and b=build number. All but the major version may be omitted. Example version strings are "220.127.116.11" and "2.1." If you want to set the type version, you must pass a string that follows this format.