function check_all(form_name)
{
	f = eval("document." + form_name)
	if (f[0].checked == true)
	{
		for (i = 0; i < f.length; i++)
		{
			f[i].checked = true;
		}
	}
	else
	{
		for (i = 0; i < f.length; i++)
		{
			f[i].checked = false;
		}
	}
}