var chln_t=0;
function chln(t,l){
	if(chln_t)return;
	chln_t=setTimeout('clearTimeout(chln_t);chln_t=0;',800);
	if(typeof(t.value)!='undefined' && t.value.length>l){
		t.value=t.value.substr(0,l);
		alert(l+' character(s) maximum!');
	}
}