Geoff Chappell - Software Analyst
The IVersionHost methods are (as ordered in the virtual function table after the IUnknown methods):
HRESULT QueryUseLocalVersionVector (BOOL *);
HRESULT QueryVersionVector (IVersionVector *);
in which IVersionVector is an undocumented interface.
The IVersionHost interface is implemented in SHDOCVW version 5.0 to 6.0, and IEFRAME version 7.0 and higher.
Though this interface dates from as long ago as 1999, it is still not documented by Microsoft as late as the January 2007 edition of the Windows Software Development Kit (SDK).