var d = document;
function invert_visibility (s_id)
{
	var o = d.getElementById(s_id);
	var v = (o.style.visibility == 'visible');
	o.style.visibility = (!v?'visible':'hidden');
	o.style.display = (!v?'block':'none');
}

function set_value (s_id, value)
{
	_(s_id).value=value;
}

function _(s_id)
{
	return d.getElementById(s_id);
}

function add_event(elem, type, h)
{
	if (elem.attachEvent)
	{
		elem.attachEvent ('on' + type, h)
	}

	if (elem.addEventListener)
	{
		elem.addEventListener (type, h, FALSE)
	}
}