function Querystring(qs) 
{
            this.params = new Object();
            this.get=Querystring_get;
            if (qs == null)
                        qs=location.search.substring(1,location.search.length);
            if (qs.length == 0) 
                        return;
            qs = qs.replace(/\+/g, ' ');
            var args = qs.split('&');
            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;
                        this.params[name] = value;
            }
}

function Querystring_get(key, default_) 
{
            if (default_ == null) 
                        default_ = null;
            var value=this.params[key];
            if (value==null) 
                        value=default_;
            return value
}

function GetPageParameter(theParam , theDefault)
{
            var qs = new Querystring()
            var ret = qs.get(theParam,theDefault);
            return ret;
}