function showSubNav (field)
{
	hiddenSubsNav();
	document.getElementById(field).style.display = 'block';
}

function hiddenSubsNav()
{
	subNavlist = document.getElementById("nav_list");
	num = subNavlist.getElementsByTagName("p").length;
	for(i=0;i<num;i++){
		subNavlist.getElementsByTagName("p")[i].style.display = "none";
	}
}