function ShowSemSchedules ($resource_id, $semester_id = null, $timespan = 'sem_time') {
$sem = new SemesterData();
if (!$semester_id){
$this->semester = $sem->getCurrentSemesterData();
} else {
$this->semester = $sem->getSemesterData($semester_id);
}
$this->timespan = $timespan;
if ($this->timespan == 'sem_time'){
$next_sem = $sem->getNextSemesterData($this->semester['vorles_ende']);
$this->start_time = $this->semester['vorles_ende'];
$this->end_time = is_array($next_sem) ? $next_sem['vorles_beginn'] : $this->semester['ende'];
} else {
$this->start_time = $this->semester['vorles_beginn'];
$this->end_time = $this->semester['vorles_ende'];
}
parent::ShowSchedules($resource_id);
}