function switchf(welke){
	if(welke=="cat"){
		if($('kcat').className!="open"){
			$('kcat').className = "open";
			$('cat').className = "open";
			$('kmerk').className = "";
			$('merk').className = "";			
		}		
	}else{
		if($('kmerk').className!="open"){
			$('kmerk').className = "open";
			$('merk').className = "open";
			$('kcat').className = "";
			$('cat').className = "";
		}
	}
}