//Browser detection, based on DOM
var hide = "hidden"; var show = "visible";    //if IE                                      
IE = true;
NS = false;
NS6 = false;

if (document.getElementById && !document.all) {  //if NS6
    NS6 = true;
    IE = false;
}
else if (document.layers) {   				//if NS4
    NS = true;
    IE = false;
    var hide = "hiden"; var show = "show";
}


//Layer manipulation

var visibleLyr = 0; 			// keeps information about visible layer
// First, we'll made browser compliant objects, which we'll use to manipulate with layers.
var popUp = new Array();  //place were we keep browser compliant layer object								

function layPre() {
    if (sloj != null) {
        if (IE) {
            for (i = 0; i < sloj.length; i++) {
                popUp[i] = eval('document.all.' + sloj[i] + '.style');
            }
        }
        else if (NS6) {
            for (i = 0; i < sloj.length; i++) {
                popUp[i] = eval("document.getElementById('" + sloj[i] + "').style");
            }
        }
        else {													//NS4
            for (i = 0; i < sloj.length; i++) {
                popUp[i] = document.eval(sloj[i]);
            }
        }
    }
}

//then we'll write a function to manipulate layers
function showLyr(lyrNo) { //makes layer visible
    var lyrNo; 		//number of layer in popUp array
    popUp[visibleLyr].visibility = hide;
    popUp[lyrNo].visibility = show;
    visibleLyr = lyrNo;
}

function hideLyr() { popUp[visibleLyr].visibility = hide; } //makes layer hidden