I suggest you define attribute type 'name' before its subtypes. I suggest you define object class 'person' before its subclass 'organizationalPerson'. Object class 'residentialPerson' does not need 'l' in the MAY part, since it already is in the MUST part. Object classes 'organizationalPerson' and 'residentialPerson' do not need 'telephoneNumber' in their MAY parts, since it already is in 'person's MAY part. -- Hallvard