This interface will be used by service ImportFilter or
ExportFilter to support loading/saving of documents in
different formats. The target/source of such filter operations must
be known before filtering will be started.
(see XImporter and XExporter too)
Otherwise this interface can't work right.
The given MediaDescriptor holds all neccessary information
about the document.
Don't hold hard references to the descriptor items. You must copy needed information!
Otherwise we couldn't destroy (for example) an existing input stream!
Parameter aDescriptor
the MediaDescriptor describing the respective document.
Returns
a boolean value indicating whether the filter operation was successful or not.