function controllo_form() {
// define(n,type,HTMLname,min,max,d)
// 
// n = name of the input field (Required)
// type= string, num, email (Required)
// min = the value must have at least [min] characters (Optional)
// max = the value must have maximum [max] characters (Optional)
// d = (Optional)
// -----------------------------------------------------------------------------

define('element_1_1','string','element_1_1');
define('element_1_2','string','element_1_2');
define('element_2','string','element_2');
define('element_3','email','element_3');
define('element_4','num','element_4');
define('element_5','string','element_5');
define('element_7','string','element_7');
define('element_8','string','element_8');
define('element_9','string','element_9');
validate();


// Cambiare nome form a fine pagina   document.formprev.submit();
}




// -----------------------------------------------------------------------------
// Initializing script  - setting global variables
// -----------------------------------------------------------------------------
var checkObjects		= new Array(); 	// Array containing the objects to validate.
var errors				= ""; 			// Variable holding the error message.
var returnVal			= false; 		// General return value. The validated form will only be submitted if true.

// -----------------------------------------------------------------------------

function define(n,type,HTMLname,min,max,d){
	var p;
	var i;
	var x;
	if(!d) d=document;
	if((p=n.indexOf("?"))>0&&parent.frames.length){
    	d=parent.frames[n.substring(p+1)].document;
    	n=n.substring(0,p);
    }
	if(!(x=d[n])&&d.all) x=d.all[n];
	
  	for (i=0;!x&&i<d.forms.length;i++){
  		x=d.forms[i][n];
  	}
	for(i=0;!x&&d.layers&&i<d.layers.length;i++){
		x=define(n,type,HTMLname,min,max,d.layers[i].document);
		return x;		
	}
	
	// Create Object. The name will be "V_something" where something is the "n" parameter above.
	eval("V_"+n+" = new formResult(x,type,HTMLname,min,max);");
	checkObjects[eval(checkObjects.length)] = eval("V_"+n);
}

// -----------------------------------------------------------------------------
// formResult - Used internally to create the objects
// -----------------------------------------------------------------------------
function formResult(form,type,HTMLname,min,max){
	this.form = form;
	this.type = type;
	this.HTMLname = HTMLname;
	this.min  = min;
	this.max  = max;
}

// -----------------------------------------------------------------------------
// validate - Call this function onSubmit and return the "returnVal". (onSubmit="validate();return returnVal;")
// -----------------------------------------------------------------------------
function validate(){
	if(checkObjects.length>0){
		errorObject = "";
	
		for(i=0;i<checkObjects.length;i++){
			validateObject 			= new Object();
			validateObject.form 	= checkObjects[i].form;
			validateObject.HTMLname = checkObjects[i].HTMLname;
			validateObject.val 		= checkObjects[i].form.value;
			validateObject.len 		= checkObjects[i].form.value.length;
			validateObject.min 		= checkObjects[i].min;
			validateObject.max 		= checkObjects[i].max;
			validateObject.type 	= checkObjects[i].type;

			inputx = document.getElementById(validateObject.HTMLname);inputx.className ='element text medium';
		

			//Debug alert line
			//alert("validateObject: "+validateObject+"\nvalidateObject.val: "+validateObject.val+"\nvalidateObject.len: "+validateObject.len+"\nvalidateObject.min,validateObject.max: "+validateObject.min+","+validateObject.max+"\nvalidateObject.type: "+validateObject.type);
			
			// Checking input. If "min" and/or "max" is defined the input has to be within the specific range
			if(validateObject.type == "num" || validateObject.type == "string"){
				if((validateObject.type == "num" && validateObject.len <= 0) || (validateObject.type == "num" && isNaN(validateObject.val))){
				errors+= "y"; inputx = document.getElementById(validateObject.HTMLname); inputx.className ='error';
				} else if (validateObject.min && validateObject.max && (validateObject.len < validateObject.min || validateObject.len > validateObject.max)){
				errors+= "y"; inputx = document.getElementById(validateObject.HTMLname); inputx.className ='error';
				} else if (validateObject.min && !validateObject.max && (validateObject.len < validateObject.min)){
				errors+= "y"; inputx = document.getElementById(validateObject.HTMLname); inputx.className ='error';
				} else if (validateObject.max && !validateObject.min &&(validateObject.len > validateObject.max)){
				errors+= "y"; inputx = document.getElementById(validateObject.HTMLname); inputx.className ='error';
				} else if (!validateObject.min && !validateObject.max && validateObject.len <= 0){
				errors+= "y"; inputx = document.getElementById(validateObject.HTMLname); inputx.className ='error';
				}
			} else if(validateObject.type == "email"){
				// Checking existense of "@" and ".". The length of the input must be at least 5 characters. The "." must neither be preceding the "@" nor follow it.
				if((validateObject.val.indexOf("@") == -1) || (validateObject.val.charAt(0) == ".") || (validateObject.val.charAt(0) == "@") ||(validateObject.len < 6) || (validateObject.val.indexOf(".") == -1) || (validateObject.val.charAt(validateObject.val.indexOf("@")+1) == ".") || (validateObject.val.charAt(validateObject.val.indexOf("@")-1) == ".")){
				errors+= "y"; inputx = document.getElementById(validateObject.HTMLname); inputx.className ='error';
				}
			}

			
				
			
		}

	}
	// Used to set the state of the returnVal. If errors -> show error messages in chosen language
	if(errors){
		errors = "";
		returnVal = false;
	} else {
		returnVal = true;
		 document.formprev.submit();
	}
}