for(StringTokenizer st = new StringTokenizer(s, ".");
box!=null && st.hasMoreTokens();
box = box.slash(st.nextToken(), false));
if (box==null) return null;
for(StringTokenizer st = new StringTokenizer(s, ".");
box!=null && st.hasMoreTokens();
box = box.slash(st.nextToken(), false));
if (box==null) return null;