treno = new Array();
treno[1] = new Image;
treno[1].src = "img/map01.gif";
treno[2] = new Image;
treno[2].src = "img/map02.gif";
treno[3] = new Image;
treno[3].src = "img/map03.gif";

function swMap(n){
	newsrc = 'img/map0' + n + '.gif';
	document['mappa'].src = treno[n].src;
	return;
}

document.write("<div id='zoom'>");

document.write ("zoom: ");
mapclass = "pari";
for (i=1;i<=3;i++) {
	if (mapclass == "pari") mapclass = "dispari";
	else mapclass = "pari";
	document.write("<a href='#' onClick='javascript:swMap("+i+")' class = '"+mapclass+"'>"+i+"</a>");
}
document.write("</div>");
document.write ("<img src='img/map01.gif' id='mappa' name='mappa'/><br/><br/>");