LDAP filter is used as a search filter.

E.g., setting LDAP filter to (|(givenName=%*)(sn=%*)) the system will use this filter when requesting entries from the LDAP server. % will be replaced with the entered prefix e.g. searching for "Jo" will give the filter (|(givenName=Jo*)(sn=Jo*)) resulting in a search for "given name" starting with a "Jo" or "surname" starting with "Jo".