LDAP Search with non-existent attributes

W’re comparing various LDAP server setups; and we are wondering what the ‘correct’ search result is for a search which is done such as '(|(|(|(givenname=fred*)(sn=fred*)(mail=fred*)(cn=fred*) in a situation where we have records which do not have a certain attribute (e.g. no givenname or cn) — e.g. a record as light weight as: dn: uid= 1234 objectClass: person uid: 1234 sn: fred fred telephoneNumber: 1234 As we notice that some servers will return this given above query; and some do not. And I cannot find the exact spot in the RFC where the
‘correct’ behaviour is mentioned. Would anyone have a pointer or a suggestion ? And would OpenLDAP 2.4 be intentionally more accommodating than the spec ? Dw.