function sprite(div_id, height, anc)
{
var div_el = document.getElementById(div_id);
div_el.style.backgroundPosition = '0 ' + height;
 view(anc);  //optional
}

function view(anc) 
{
var frm = document.getElementById('frame');
var links = frm.getElementsByTagName('a');
var link, i = 0;
while (link = links[i++])
{
link.className = (link != anc) ? 'off' : 'on';
}
}