function addparam() {
	if (document.getElementById("frmRic") && document.getElementById("frmRic").soloAuto.checked==true){	//se la checkbox è checked
		//guardo se c'è già il parametro
		if(window.location.search.indexOf("soloAuto")!=-1){
			var curUrl = window.location.search;
		 	var splitted = curUrl.split("&");
			 for(var i=0;i<splitted.length;i++){
			 	var par = splitted[i];
				if(par.indexOf("soloAuto")!=-1){
					var div = par.split("=");
					div[1] = "on";
					splitted[i] = div.join("=");
					break;
				}
			 }
			 var newsearch = splitted.join("&");
			 window.location = window.location.protocol+window.location.pathname+newsearch;
		}
		else{
			var newurl = window.location+'&soloAuto=on';
			window.location = newurl;	
		}
	
	return true;
	}
	else {// checkbox non checked
	 var curUrl = window.location.search;
	 var splitted = curUrl.split("&");
	 for(var i=0;i<splitted.length;i++){
	 	var par = splitted[i];
		if(par.indexOf("soloAuto")!=-1){
			/*
			var div = par.split("=");
			div[1] = "off";
			splitted[i] = div.join("=");
			*/
			splitted.splice(i,1);
			break;
		}
	 }
	 var newsearch = splitted.join("&");
	 //alert("nuovi params: "+newsearch);
	 window.location = window.location.protocol+window.location.pathname+newsearch;
	 return true;
	}
}