function checkAll()
{
  var f = document.forms['list'];
  var i;
  for (i=0; i<f.length; i++) {
    if (f[i].type == "checkbox")
      f[i].checked = !f[i].checked;
  }
}
function invertAll(headerfield, checkform, mask)
{
	for (var i = 0; i < checkform.length; i++)
	{
		if (typeof(checkform[i].name) == "undefined" || (typeof(mask) != "undefined" && checkform[i].name.substr(0, mask.length) != mask))
			continue;

		if (!checkform[i].disabled)
			checkform[i].checked = headerfield.checked;
	}
}