function showhide(layer_ref)
{
    var state = null;
    if (document.getElementById)
    {
        state = document.getElementById(layer_ref).style.display;
    }
    if (state != null && state == 'block')
    {
        state = 'none';
    } 
    else
    { 
        state = 'block'; 
    }
    if (document.getElementById)
    {
        hza = document.getElementById(layer_ref);
        hza.style.display = state;
    }
    else if (document.all)
    {
        //IS IE 
        eval( "document.all." + layer_ref + ".style.display = state"); 
    } 
    else if (document.layers)
    {
        //IS NETSCAPE 4 or below
        document.layers[layer_ref].display = state;
    }
}