var elem, prevelem, evisibility, id, imageid, previd;
previd = "";
var plusimg = new Image();
plusimg.src = '/txdot_images/plus' + '.gif'
var minusimg = new Image ();
minusimg.src = '/txdot_images/minus' + '.gif'
function showHideContent(id)
    {
    if (previd != "")
        {
        if (previd != id)
            {
            elem = document.getElementById(previd);
            evisibility = elem.style.visibility;
            if (evisibility != 'hidden') 
                {
                elem.style.display = 'none';
                elem.style.visibility = 'hidden';
                imageid = previd + 'Image';
                document.images[imageid].src = plusimg.src;
                }
            }
        }
    elem = document.getElementById(id);
    evisibility = elem.style.visibility;
    if (elem) 
        {
        if (evisibility == 'hidden') 
            {
            elem.style.display = 'block';
            elem.style.visibility = 'visible';
            imageid = id + 'Image';
            document.images[imageid].src = minusimg.src;
            } 
        else
            {
            elem.style.display = 'none';
            elem.style.visibility = 'hidden';
            imageid = id + 'Image';
            document.images[imageid].src = plusimg.src;
            }
        previd = id;
        }
    }