There are some inconsistencies in the MSDN documentation of the ptd (DVTARGETDEVICE *) and hdcTargetDev in the IViewObject::Draw documentation at the following location:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms688655(v=vs.85).aspx
http://msdn.microsoft.com/en-us/library/windows/desktop/ms688655(v=vs.85).aspx