var imageExt = ".gif";
var imageOn = "_on";
/*****************************************************************
 this function takes an image name, image file name, 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/[fileName].gif 
		or
	/images/[fileName]_on.gif
	
 and that images in the html are named imgName	
*****************************************************************/

function swapImg (imgName, fileName, onoff)
{
	//alert("swapImage(" + imgName + "," + fileName + "," + 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 = "";
	
	//alert("new image name = " + imagePath + fileName + onoffText + imageExt);
	document.images[imgName].src = imagePath + fileName + onoffText + imageExt;
}