ONC is based on calling conventions used in Unix and the C programming language. It serializes data using the XDR, which has also found some use to encode and decode data in files that are to be accessed on more than one platform. ONC then delivers the XDR payload using either UDP or TCP. Access to RPC services on a machine are provided via a port mapper that listens for queries on a well-known port, port 111 over UDP and TCP.
Implementations of ONC RPC exist in most Unix-like systems. Microsoft supplies an implementation for Windows in their Microsoft Windows Services for UNIX product; in addition, a number of third-party implementation of ONC RPC for Windows exist, including versions for C/C++, Java, and .NET (see external links).
ONC RPC is described in RFC 1831. Authentication mechanisms used by ONC RPC are described in RFC 2695, RFC 2203, and RFC 2623.