var Roll=new Array();

function RollOver(on_url)
{       this.on        = new Image();
        this.on.src    = on_url;
}

function flip ()
{       if(arguments.length==1) arguments[1]=arguments[0];
        for(i=0 ; i<arguments.length ; i+=2){
                temp = document.images[arguments[i]].src;
                document.images[arguments[i]].src  = Roll[arguments[i+1]].on.src;
                Roll[arguments[i+1]].on.src = temp;
        }
}