diff --git a/config/dav.inc.php.sample b/config/dav.inc.php.sample
index 9f56d50..606f3ed 100644
--- a/config/dav.inc.php.sample
+++ b/config/dav.inc.php.sample
@@ -1,123 +1,124 @@
 <?php
 
 /*
  +-------------------------------------------------------------------------+
  | Configuration for the Kolab DAV server                                  |
  |                                                                         |
  | Copyright (C) 2013, Kolab Systems AG                                    |
  |                                                                         |
  | This program is free software: you can redistribute it and/or modify    |
  | it under the terms of the GNU Affero General Public License as          |
  | published by the Free Software Foundation, either version 3 of the      |
  | License, or (at your option) any later version.                         |
  |                                                                         |
  | This program is distributed in the hope that it will be useful,         |
  | but WITHOUT ANY WARRANTY; without even the implied warranty of          |
  | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the            |
  | GNU Affero General Public License for more details.                     |
  |                                                                         |
  | You should have received a copy of the GNU Affero General Public License|
  | along with this program. If not, see <http://www.gnu.org/licenses/>.    |
  |                                                                         |
  +-------------------------------------------------------------------------+
 */
 
 $config = array();
 
 // The HTTP path to the iRony root directory.
 // Set to / if the service is registered as document root for a virtual host
 $config['base_uri'] = '/iRony/';
 
 // User agent string written to kolab storage MIME messages
 $config['useragent'] = 'Kolab DAV Server libkolab/' . RCUBE_VERSION;
 
 // Type of Auth cache. Supported values: 'db', 'apc' and 'memcache'.
 // Note: This is only for username canonification map.
 $config['kolabdav_auth_cache'] = 'db';
 
 // lifetime of the Auth cache, possible units: s, m, h, d, w
 $config['kolabdav_auth_cache_ttl'] = '1h';
 
 // enable debug console showing the internal function calls triggered
 // by http requests. This will write log to /var/log/iRony/console
 $config['kolabdav_console'] = false;
 
 // enable per-user debugging if /var/log/iRony/<username>/ folder exists
 $config['kolabdav_user_debug'] = false;
 
 // enable logging of full HTTP payload
 // (bitmask of these values: 2 = HTTP Requests, 4 = HTTP Responses)
 $config['kolabdav_http_log'] = 0;
 
 // expose iTip invitations from email inbox in CalDAV scheduling inbox.
 // this will make capable CalDAV clients process event invitations and
 // as a result, the invitation messages are removed from the email inbox.
 // WARNING: this feature is still experimental and not fully implemented.
 // See https://git.kolab.org/T93 for details and implementation status.
 $config['kolabdav_caldav_inbox'] = false;
 
 // Enables the CardDAV Directory Gateway Extension by exposing an
 // LDAP-based address book in the pricipals address book collection.
 // Properties of this option are the same as for $config['ldap_public'] entries.
+// NOTE: Mapping of (additional) 'uid' and 'changed' fields is required!
 /*
 $config['kolabdav_ldap_directory'] = array(
     'name'           => 'Global Address Book',
     'hosts'          => 'localhost',
     'port'           => 389,
     'use_tls'        => false,
     // If true the base_dn, bind_dn and bind_pass default to the user's credentials.
     'user_specific'  => false,
     // It's possible to bind with the current user's credentials for individual address books.
     // The login name is used to search for the DN to bind with
     'search_base_dn'            => 'ou=People,dc=example,dc=org',
     'search_bind_dn'            => 'uid=kolab-service,ou=Special Users,dc=example,dc=org',
     'search_bind_pw'            => 'Welcome2KolabSystems',
     'search_filter'             => '(&(objectClass=inetOrgPerson)(mail=%fu))',
     // When 'user_specific' is enabled following variables can be used in base_dn/bind_dn config:
     // %fu - The full username provided, assumes the username is an email
     //       address, uses the username_domain value if not an email address.
     // %u  - The username prior to the '@'.
     // %d  - The domain name after the '@'.
     // %dc - The domain name hierarchal string e.g. "dc=test,dc=domain,dc=com"
     // %dn - DN found by ldap search when search_filter/search_base_dn are used
     'base_dn'        => 'ou=People,dc=example,dc=org',
     'bind_dn'        => 'uid=kolab-service,ou=Special Users,dc=example,dc=org',
     'bind_pass'      => 'Welcome2KolabSystems',
     'ldap_version'   => 3,
     'filter'         => '(objectClass=inetOrgPerson)',
     'search_fields'  => array('displayname', 'mail'),
     'sort'           => array('displayname', 'sn', 'givenname', 'cn'),
     'scope'          => 'sub',
     'searchonly'     => true,  // Set to false to enable listing
     'sizelimit'      => '1000',
     'timelimit'      => '0',
     'fieldmap'       => array(
         // Roundcube        => LDAP
         'name'              => 'displayName',
         'surname'           => 'sn',
         'firstname'         => 'givenName',
         'middlename'        => 'initials',
         'prefix'            => 'title',
         'email:work'        => 'mail',
         'email:other'       => 'alias',
         'phone:main'        => 'telephoneNumber',
         'phone:work'        => 'alternateTelephoneNumber',
         'phone:mobile'      => 'mobile',
         'phone:work2'       => 'blackberry',
         'street'            => 'street',
         'zipcode'           => 'postalCode',
         'locality'          => 'l',
         'organization'      => 'o',
         'jobtitle'          => 'title',
         'photo'             => 'jpegphoto',
         // required for internal handling and caching
         'uid'               => 'nsuniqueid',
         'changed'           => 'modifytimestamp',
     ),
 );
 */
 
 // Enable caching for LDAP directory data.
 // This is recommended with 'searchonly' => false to speed-up sychronization of multiple clients
 // $config['kolabdav_ldap_cache'] = 'memcache';
 // $config['kolabdav_ldap_cache_ttl'] = 600;   // in seconds