A control consists of an oid identifying the control, an optional value, and an optional flag for criticality.
The options LDAP_OPT_DEREF, LDAP_OPT_SIZELIMIT, LDAP_OPT_TIMELIMIT, LDAP_OPT_PROTOCOL_VERSION and LDAP_OPT_ERROR_NUMBER have integer value, LDAP_OPT_REFERRALS and LDAP_OPT_RESTART have boolean value, and the options LDAP_OPT_HOST_NAME, LDAP_OPT_ERROR_STRING and LDAP_OPT_MATCHED_DN have string value. The first example illustrates their use. The options LDAP_OPT_SERVER_CONTROLS and LDAP_OPT_CLIENT_CONTROLS require a list of controls, this means that the value must be an array of controls. A control consists of an oid identifying the control, an optional value, and an optional flag for criticality. In PHP a control is given by an array containing an element with the key oid and string value, and two optional elements. The optional elements are key value with string value and key iscritical with boolean value. iscritical defaults to FALSE if not supplied. See also the second example below.