Returns whether this XamlMember represents a member that is not resolvable by the backing system that is used for type and member resolution.
Assembly: System.Xaml (in System.Xaml.dll)
This method may be invoked when a caller gets a value from IsUnknown. The default implementation returns results that are based on either internal reflection or checking for a null value of UnderlyingMember, processing in that order.
Override this method if you want to report uniform results for an entire XamlMember derived class, or if you have specialized metadata available to determine this on a per-case basis.