// Detect if browser is Netscape 3 + or IE 4 +.
bName = navigator.appName;
bVer = parseInt(navigator.appVersion);
    if ((bName == "Netscape" && bVer >= 3) || 
        (bName == "Microsoft Internet Explorer" && bVer >= 4)) br = "n3"; 
    else br = "n2";
;

// Create image objects, preload all active and inactive images.
    if (br== "n3") { 
    nav01on = new Image();
    nav01on.src = "/giswr/images/nav01b.gif";
    nav02on = new Image();
    nav02on.src = "/giswr/images/nav02b.gif";
    nav03on = new Image();
    nav03on.src = "/giswr/images/nav03b.gif";
    nav04on = new Image();
    nav04on.src = "/giswr/images/nav04b.gif";
 
    nav01off = new Image();
    nav01off.src = "/giswr/images/nav01a.gif";
    nav02off = new Image();
    nav02off.src = "/giswr/images/nav02a.gif";
    nav03off = new Image();
    nav03off.src = "/giswr/images/nav03a.gif";
    nav04off = new Image();
    nav04off.src = "/giswr/images/nav04a.gif";    
    }

// Function to "activate" images.
function imgAct(imgName) {
    if (br == "n3") {
    document[imgName].src= eval(imgName + "on.src");
    }
}

// Function to "deactivate" images.
function imgInact(imgName) {
    if (br == "n3") {
    document[imgName].src= eval(imgName + "off.src");
    }
}