function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

function changeImages() {
	if (document.images && (preloadFlag == true)) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
		}
	}
}

var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		surname_over = newImage("../images/surname-over.gif");
		descriptive_over = newImage("../images/descriptive-ver.gif");
		invented_over = newImage("../images/invented-over.gif");
		connotative_over = newImage("../images/connotative-over.gif");
		bridge_over = newImage("../images/bridge-over.gif");
		arbitrary_over = newImage("../images/arbitrary-over.gif");
		preloadFlag = true;
	}
}