browserName = navigator.appName; browserVer = parseInt(navigator.appVersion);
if (browserName == "Netscape" && browserVer >= 3) { browserCheck = "ok"; }
else { 
    if (browserName == "Microsoft Internet Explorer" && browserVer >= 3) { browserCheck = "ok"; }
    else { browserCheck = "bad"; }
}
if (browserCheck == "ok") { 
b0a = new Image(); b0a.src = "tile0-17.gif";
b0b = new Image(); b0b.src = "tile0-17a.gif";
}
function imgswap( Iname1, Iname2) { if (browserCheck == "ok") { document [Iname1].src
= eval(Iname2 + ".src"); } }