Notifies the host that a new document context is being created and allows the host to optionally return a controlling unknown for the new context.
[out] An object that controls the new context.
The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.
The method succeeded.
The host does not provide a controlling object.
This method allows the host to add new functionality to the helper-provided document contexts. This method may return E_NOTIMPL or a null outer object, in which case the caller is responsible for creating the context.