The identifier of a Subordinate Reference entity is the
 distinguished name of the entry to which the entity provides a
 reference, for example, "/C=US/O=Abacus/OU=Accounts".

 The identifier of a Subordinate Reference entity is the
 same as the identifier of a Naming Context entity held by some
 other DSA.  Thus the entity provides a reference to the remote
 naming context. It is possible for the Subordinate Reference
 entity to be on the same DSA as the Naming Context entity to
 which it provides a reference.

 Refer to DSA Common_Datatypes for more information on
 how to specify a distinguished name.  Refer to the CREATE
 directive for more information on how to create a Subordinate
 Reference entity.