The power of directory service is possibility to define your own object classes, attributes, rules and so on. It also allows grouping it in schemas, which you can add to LDAP configuration.
As for now most of schemas, which you can find in Internet is organized into blocks, which contains definitions of attributes and object classes. This looks like:
attribute type definition:
attributetype ( 188.8.131.52.4.1.323184.108.40.206.9 NAME 'accountStatus' DESC 'The status of a user account: active, disabled' EQUALITY caseIgnoreIA5Match SUBSTR caseIgnoreSubstringsMatch SYNTAX 220.127.116.11.4.1.1418.104.22.168.26 SINGLE-VALUE )