<!-- Original:  Cyanide_7 (leo7278@hotmail.com) -->
<!-- Web Site:  http://members.xoom.com/cyanide_7 -->
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;
}