LDAP schema for dovecot proxy?

Hello, I want to deploy dovecot proxy/director with the backend and authorization in LDAP. Dovecot wiki specifies only what is necessary to apply additional arguments that the scheme would have earned a proxy, but no solid LDAP schema. Is there such a scheme, such as the existing scheme

http://www.zytrax.com/books/ldap/ape/courier.html http://pro-ldap.ru/sources/schema/qmail.schema http://open.rhx.it/phamm/schema/phamm.schema

Unfortunately for the tasks they are not good because they just no dovecot-specific variables