RMI without stubs

Given the following note:

(found here)

Note: As of the J2SE 5.0 release, stub classes for remote objects no longer need to be pregenerated using the rmic stub compiler, unless the remote object needs to support clients running in pre-5.0 VMs. If your application needs to support such clients, you will need to generate stub classes for the remote objects used in the application and deploy those stub classes for clients to download. For details on how to generate stub classes, see the tools documentation for rmic [Solaris, Windows]. For details on how to deploy your application along with pregenerated stub classes, see the codebase tutorial.

My question is simple: How does RMI work without stubs ?