var opened;

function dd(obj){

	if(document.getElementById){
		if(document.getElementById(obj).style.display=='none'){
			document.getElementById(obj).style.display='';
			if(opened  != null){
				document.getElementById(opened).style.display='none';
				}
			opened=obj;
		}else{
			document.getElementById(obj).style.display='none';
			opened=null;
			}
	}

	else if(document.all){
		if(document.all(obj).style.display=='none'){
			document.all(obj).style.display='';
			if(opened  != null){
				document.all(opened).style.display='none';
			}
			opened=obj;
		}else{
			document.all(obj).style.display='none';
			opened=null;
		}
	}

	else if(document.layers){
		if(document.layers[obj].display=='none'){
			document.layers[obj].display='';
			if(opened  != null){
				document.layers[obj].display='none';
				}
				opened=obj;
			}else{
				document.layers[obj].display='none';
				opened=null;
			}
		}

}