The [[X.500]] directory services were accessed via the [[X.500]] Directory Access Protocol ([[DAP]]), which required the Open Systems Interconnection ([[OSI]]) protocol stack. The advent of LDAP removed the necessity of the [[OSI]] protocol. | The [[X.500]] directory services were accessed via the [[X.500]] Directory Access Protocol ([[DAP]]), which required the Open Systems Interconnection ([[OSI]]) protocol stack. The advent of LDAP removed the necessity of the [[OSI]] protocol. |