When Move or Resize is used, the calendar app is call back and the nmgp_opcao will be set to ācalendar_dropā or ācalendar_resizeā
sc_event_id will contain the calendar ID of the appointment
if (isset($_POST['nmgp_opcao'])) {
	if ($_POST['nmgp_opcao'] == 'calendar_drop' or $_POST['nmgp_opcao'] == 'calendar_resize') {
                    $id = $_POST['sc_event_id'];
                    $day_delta = $_POST['sc_day_delta']; //+ or - days
                    $time_delta = $_POST['sc_time_delta']; //+ or - minutes
                    $all_day = $_POST['sc_all_day'];
                     .... 
            }
    }
You can put this in onScriptInit
Note that this code will be executed before the appointment is modified by calendar