var isNN = (navigator.appName.indexOf("Netscape")!=-1); 
function autoTab(input,len, e) { 
	var keyCode = (isNN) ? e.which : e.keyCode; 
	var filter = (isNN) ? [0,8,9] : [0,8,9,16,17,18,37,38,39,40,46]; 
	if(input.value.length >= len && !containsElement(filter,keyCode)) { 
		input.value = input.value.slice(0, len); 
		input.form[(getIndex(input)+1) % input.form.length].focus(); 
	} 

function containsElement(arr, ele) { 
	var found = false, index = 0; 
	while(!found && index < arr.length) 
		if(arr[index] == ele) 
			found = true; 
		else 
			index++; 
	return found; 
} 

function getIndex(input) { 
	var index = -1, i = 0, found = false; 
	while (i < input.form.length && index == -1) 
		if (input.form[i] == input) 
			index = i; 
		else i++; 
	return index; 
} 
return true; 
}