function Querystring(qs)
{ // optionally pass a querystring to parse
    this.params = new Object()
    this.get=Querystring_get

    if (qs == null)
	    qs=location.search.substring(1,location.search.length)
    
    if (qs.length == 0) return
    
    // Turn <plus> back to <space>
    // See: http://www.w3.org/TR/REC-html40/interact/forms.html#h-17.13.4.1
    qs = qs.replace(/\+/g, ' ')
    var args = qs.split('&') // parse out name/value pairs separated via &

    // split out each name=value pair
    for (var i=0;i<args.length;i++)
    {
	    var value;
	    var pair = args[i].split('=')
	    var name = unescape(pair[0])

	    if (pair.length == 2)
		    value = unescape(pair[1])
	    else
		    value = name
    	name = name.toLowerCase();
	    this.params[name] = value
    }
}

function Querystring_get(key, default_)
{
    key = key.toLowerCase();
	// This silly looking line changes UNDEFINED to NULL
	if (default_ == null) default_ = null;
	
	var value=this.params[key]
	if (value==null) value=default_;
	
	return value
}