<!-- hide script from old browsers
//detect browser:
browserName = navigator.appName; 
         browserVer = parseInt(navigator.appVersion);
             if (browserName == "Netscape" && browserVer >= 3) browserVer = "1";
                 else if (browserName == "Microsoft Internet Explorer" && browserVer == 4) browserVer = "1";
             else browserVer = "2";

//preload images:
if (browserVer == 1) {
        a1 = new Image(60,20);
        a1.src = "imas/menu_ninicio.gif";      
        a2 = new Image(60,20);
        a2.src = "imas/menu_hinicio.gif";
        b1 = new Image(127,20);
        b1.src = "imas/menu_nacerca.gif";      
        b2 = new Image(127,20);
        b2.src = "imas/menu_hacerca.gif";
        c1 = new Image(81,20);
        c1.src = "imas/menu_nservicios.gif";      
        c2 = new Image(81,20);
        c2.src = "imas/menu_hservicios.gif";
        d1 = new Image(76,20);
        d1.src = "imas/menu_nmaquila.gif";      
        d2 = new Image(76,20);
        d2.src = "imas/menu_hmaquila.gif";
        e1 = new Image(91,20);
        e1.src = "imas/menu_nportaf.gif";      
        e2 = new Image(91,20);
        e2.src = "imas/menu_hportaf.gif";
        f1 = new Image(74,20);
        f1.src = "imas/menu_nempleo.gif";      
        f2 = new Image(74,20);
        f2.src = "imas/menu_hempleo.gif";
        g1 = new Image(79,20);
        g1.src = "imas/menu_ncontacto.gif";      
        g2 = new Image(79,20);
        g2.src = "imas/menu_hcontacto.gif";

}

//image swapping function:
function menuActivo(imgDocID, imgObjName, comment) {
if (browserVer == 1) {
        document.images[imgDocID].src = eval(imgObjName + ".src");
        window.status = comment; return true;
}}
//end hiding -->