var target = "top"; 
function jump(){ 
	var url = document.form1.select.options[document.form1.select.selectedIndex].value; 
	if(url != "" ){ 

	if(target == 'top'){ 
		top.location.href = url; 
		}

	else if(target == 'blank'){ 
		window.open(url, 'window_name'); 
		}

	else if(target != ""){
		eval('parent.' + target + '.location.href = url'); 
		}
	else{
		location.href = url; 
		}
	}
}