var bolMark = true;

function markall()
{
	if (bolMark)
	{
		for (var i = 0; i < document.messform.length; i++)
		{
			if (document.messform.elements[i].type == 'checkbox')
			{
				document.messform.elements[i].checked = true;
			}
		}
	}
	else
	{
		for (var i = 0; i < document.messform.length; i++) {
			if (document.messform.elements[i].type == 'checkbox')
			{
				document.messform.elements[i].checked = false;
			}
		}
	}
	bolMark = !bolMark;
}