var tab = document.getElementsByTagName('tr');

function hideElements(obj)
{
	if(obj.checked==true)
	{
		for(i=6; i<tab.length-5; i++) tab[i].style.display='none';
	}
	else
	{
		for(i=6; i<tab.length-5; i++) tab[i].style.display='table-row';
	}
	document.getElementById('submit_button').disabled = false;
}

function showElements(obj)
{
	if(obj.checked==true)
	{
		for(i=6; i<tab.length-5; i++) tab[i].style.display='table-row';
	}
	else
	{
		for(i=6; i<tab.length-5; i++) tab[i].style.display='none';
	}
	document.getElementById('submit_button').disabled = false;
}