function validate_required(field,alerttxt)
{
	with (field)
	{
		if (value==null||value=="")
			{alert(alerttxt);return false}
		else {return true}
	}
}

function toggleLayer(whichLayer)
{
     if (document.getElementById)
     {
          // this is the way the standards work
          var style2 = document.getElementById(whichLayer).style;
          style2.display = style2.display? "":"block";
     }
     else if (document.all)
     {
          // this is the way old msie versions work
          var style2 = document.all[whichLayer].style;
          style2.display = style2.display? "":"block";
     }
     else if (document.layers)
     {
          // this is the way nn4 works
          var style2 = document.layers[whichLayer].style;
          style2.display = style2.display? "":"block";
     }
}

function popupPage(page_pop) {

if (page_pop == "ato") {var page = "../../data/html/ato.html";}
if (page_pop == "gps") {var page = "../../data/html/gps.html";}
if (page_pop == "mbr") {var page = "../../data/html/mbr.php";}
if (page_pop == "pct") {var page = "../../data/html/photocredit.php";}

windowprops = "height=200,width=400,location=no,"
+ "scrollbars=yes,menubars=no,toolbars=no,resizable=no";

window.open(page, "Popup", windowprops);
}

function confirmSubmit(message)
	{
	var agree=confirm(message);
	if (agree)
		return true ;
	else
		return false ;
	}