The service transport handle, SVCXPRT, contains a single data area for decoding arguments and encoding results. Therefore, in the default, single-threaded mode, this structure cannot be freely shared between threads that call functions that perform these operations. However, when a server is operating in the MT Auto or User modes, a copy of this structure is passed to the service dispatch procedure in order to enable concurrent request processing. Under these circumstances, some routines that would otherwise be unsafe become safe. Unless otherwise noted, the server interfaces are generally MT safe. See the rpc_svc_calls(3NSL) man page for more details on safety for server-side interfaces.