The ACL database contains only ACLs; its records have no headers. The records are indexed by ACL UUIDs. Here we do not even explicitly declare the conversion routine (rdacl_convert); it is generated by IDL (from a definition in dce/dceacl.idl). All we have to do is pass the routine's name to the dce_db_open( ) call that opens this database.
Note that this is the database that the ACL library has to have access to; this access is set up by a call to dce_acl_register_object_type( ), registration then allows the ACL library to derive any or all of these three things from an object name (the application's resolver routine has to help out in this, of course).