var divList = new Array('extratext1', 'extratext2', 'extratext3');
function showDiv(divId)
{
	for(i=0; i<(divList.length); i++)
	{
		//alert(divList[i]);
		if(divId == divList[i])	document.getElementById(divList[i]).style.display='block';
		else	document.getElementById(divList[i]).style.display='none';
	}
}