var state = 'none';

function showhide(layer_ref) {

    if (state == 'none') {
        state = 'block';
    }
    else {
        state = 'none';
    }
    if (document.all) { //IS IE 4 or 5 (or 6 beta) 
        eval("document.all." + layer_ref + ".style.display = state");
    }
    if (document.layers) { //IS NETSCAPE 4 or below 
        document.layers[layer_ref].display = state;
    }
    if (document.getElementById && !document.all) {
        hza = document.getElementById(layer_ref);
        hza.style.display = state;
    }
}