void NLMPROC4_NULL(void) = 0;
The NULL procedure does no work. It is made available in all RPC services to allow server response testing and timing.
It is important that this procedure do no work at all so that it can be used to measure the overhead of processing a service request. By convention, the NULL procedure should never require any authentication.
It is possible that some server implementations may return RPC errors based on security and authentication requirements.