ISO/IEC 9594-5:2001 specifies the Directory Access Protocol, the Directory System Protocol, the Directory Information Shadowing Protocol and the Directory Operational Binding Management Protocol fulfilling the abstract services specified in ITU-T Recs. X.501 ISO/IEC 9594-2, X.511 ISO/IEC 9594-3, X.518 ISO/IEC 9594-4 and X.525 ISO/IEC 9594-9.