This refers to the ability for a WinNet16 driver to perform its own operations on directories associated with the network, rather than letting the File Manager do it (WNetDirectoryNotify).
It should, in general, be a two phase operation for multiple networks, but is only a one phase operation. This is because it is only used for WFWG server level functionality (shared local drives).
As for the property dialog extensions, the MPR does not add to this functionality.