var imageExt = ".gif";
var imageOn = "_on";
/*****************************************************************
 this function takes an image name, number, and on/off flag 
 and sets an image source (used for rollover, rollout).   
   
 this function assumes that images files are named with  
 the following convention: 
	/images/[icnName].gif 
		or
	/images/[icnName]_on.gif
	
 and that images in the html are named icnName + icnNum. This is 
 especially important as there will be multiple images on the page
 with the same icnName.
	
*****************************************************************/
function toggleIcon (icnName,icnNum,onoff)
{
	var onoffText = "";
	if (onoff == 0) // if we are rolling over
		onoffText = imageOn; // be sure to include the "on" extension in the name
	else
		onoffText = "";
	// else, leave this blank
	
	//alert("image name = " + imagePath + icnName + onoffText + imageExt);
	
	// now swap images
	document.images[icnName+icnNum].src = imagePath + icnName + onoffText + imageExt;
}
/*****************************************************************


this function opens a new window for the legend on map pages


*****************************************************************/