In Example 5–14, the last argument to rpc_gss_getcred() (here, a NULL) is a user-defined cookie, with a value on return of whatever was specified by the server when the context was created. This cookie, a 4-byte value, can be used in any way appropriate for the application. RPC does not interpret the cookie. For example, the cookie can be a pointer or index to a structure that represents the context initiator. Instead of computing this value for every request, the server computes it at context-creation time, saving on request-processing time.