[SyncEvolution] adding new adress-book entries/field-definitions on the server side

Hello I was able to set up sync between my horde 4 groupware edition and my nokia n900 using syncevolution. I had to make a small improvement to the horde groupware by adding the entries homeEmail and workEmailto the frontend and the DB backend and now I can sync the normal, home- or work-email between the phone and the groupware. I just followed thios howto : http://edeca.net/wp/2010/01/modifying-fields-in-the-turba-addressbook/ I would like to add more fileds, like gender or skype account - which are pressent in the n900 adress book. Can somebody please explain to me where can i find the definitions about how to define this fileds, so the syncevolution recognize them right ? For example here is the definition of homeEmail : $attributes['homeEmail'] = array( 'label' => _("Home Email"), 'type' => 'email', 'required' => false, 'params' => array('allow_multi' => false, 'strip_domain' => false, 'link_compose' => true) ); For example I am totaly unsure about the "type" of the field gender i would like to set. Thanks in advance for an explanation Karel