function addElement(id){
	var C1, C2

	C1 = document.getElementById(id);
	C2 = document.getElementById('sel_'+id);

	if(C2.value=="-1")
		{
			C1.select;
			C1.innerText="";
		}
	else
		{
			C1.innerText = C1.innerText + (C1.innerText!=""?', ':'') + C2.value;
		}
}