Adds a simple undo unit to the collection.
HRESULT Add(
IOleUndoUnit* pUU //Pointer to undo unit to be added
);
The parent undo unit or undo manager must accept any undo unit given to it, unless it is blocked. If it is blocked, it should do nothing but return S_OK.
Windows NT: Use version 4.0 or later. New for OC96.
Windows: Use Windows 95 or later. New for OC96.
Windows CE: Unsupported.
Header: Declared in ocidl.h.