SHELL32 implements numerous COM interfaces. For some, SHELL32 has the only known implementation. Others are implemented elsewhere but SHELL32 may be thought to have the defining or standard implementation. A few interfaces are expected to be implemented widely in other executables but it is SHELL32 that is the typical user of the interface. Of all these, many are documented and many are not. I can’t hope even to catalogue all the undocumented interfaces, let alone document them, but I can at least publish the initial notes that I make on the interfaces that I come across. These notes seldom do more than list Microsoft’s names for the interface and its methods, but they should suffice as anyone’s starting point for investigating an undocumented interface that turned out to interest them.