function toggleDiv(divid) {
    var imagename = "img" + divid;
    var myimage;
    if (document.getElementById(divid).style.display == 'block') {
        document.getElementById(divid).style.display = 'none';
        myimage = "images/plus.gif";
        document.getElementById(imagename).setAttribute('src', myimage);
    } else {
        document.getElementById(divid).style.display = 'block';
        myimage = "images/minus.gif";
        document.getElementById(imagename).setAttribute('src', myimage);
    }
}