If permitted, a context initiator can request that the context acceptor act as a proxy. In such a case, the acceptor can initiate further contexts on behalf of the initiator.
Suppose someone on Machine A wants to rlogin to Machine B, and then rlogin from Machine B to Machine C. Depending on the mechanism, the delegated credential identifies B either as A or B as proxy for A.
If delegation is permitted, ret_flags can be set to GSS_C_DELEG_FLAG. The acceptor receives a delegated credential as the delegated_cred_handle argument of gss_accept_sec_context(). Delegating a credential is not the same as exporting a context. See Exporting and Importing Contexts in GSS-API. One difference is that an application can delegate that application's credentials multiple times simultaneously, while a context can only be held by one process at a time.