Geoff Chappell - Software Analyst
The IFolderType methods are (as ordered in the virtual function table after the IUnknown methods):
HRESULT GetFolderType (FOLDERTYPEID *);
The IFolderType interface is implemented in SHELL32.DLL in the version 6.00 from Windows Vista, and higher.
Though new for Windows Vista, this interface is not documented by Microsoft in the January 2007 edition of the Software Development Kit (SDK) for Windows Vista.