This is the known list of the GUIDs being used by HTML Help:
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adb880a1-d8ff-11cf-9377-00aa003b7a11 = IHHCtrl Interface
adb880a2-d8ff-11cf-9377-00aa003b7a11 = HHCtrl 4.0 Type Library
adb880a3-d8ff-11cf-9377-00aa003b7a11 = Event interface for HHCtrl
adb880a4-d8ff-11cf-9377-00aa003b7a11 = HHFind 1.0 Type Library (in HHCtrl)
adb880a5-d8ff-11cf-9377-00aa003b7a11 = Reserved for future use
adb880a6-d8ff-11cf-9377-00aa003b7a11 = HHCtrl Class (Click handler)
adb880a7-d8ff-11cf-9377-00aa003b7a11 = Reserved for future use
adb880a8-d8ff-11cf-9377-00aa003b7a11 = Reserved for future use
adb880a9-d8ff-11cf-9377-00aa003b7a11 = Reserved for future use...

d66c3421-02e5-11d1-90ab-00a0c911e8ac = HHSort 1.0 Type Library