/* Browser and version detector */
var isNS = (navigator.appName == "Netscape" && parseInt(navigator.appVersion) >= 4);

/* defines HIDDEN and VISIBLE variables for both browsers */
var HIDDEN = (isNS) ? 'hide' : 'hidden';
var VISIBLE = (isNS) ? 'show' : 'visible';

/* defines ID for both browsers */
var exp1 = (isNS) ? document.exp1 : document.all.exp1.style;
var exp2 = (isNS) ? document.exp2 : document.all.exp2.style;
var exp3 = (isNS) ? document.exp3 : document.all.exp3.style;