alfa = (   ((navigator.appName == "Netscape") 
            && (parseInt(navigator.appVersion) > 3 ))
        || ((navigator.appName == "Microsoft Internet Explorer")
            && (parseInt(navigator.appVersion) >= 4 )) );

function overBut(id)
{
	var result = false;
	
	if ( alfa )
	{
		var src  = document.images[id].src;
		var tail = "_0.gif";

		if ( src.toLowerCase().lastIndexOf(tail) == src.length - 6 )
		{
			document.images[id].src = src.substring(0, src.length - 6) + "_1.gif";
			result = true;
		}
	}
	return(result);
}

function outBut(id)
{
	var result = false;

	if ( alfa )
	{
		var src  = document.images[id].src;
		var tail = "_1.gif";

		if ( src.toLowerCase().lastIndexOf(tail) == src.length - 6 )
		{
			document.images[id].src = src.substring(0, src.length - 6) + "_0.gif";
			result = true;
		}
	}

	return false;
}