//log.debug("nncsv() first: " + _first() + "to " + this);
Buffer buf = new Buffer();
for (Field f : _first().nns()) {
String cn1 = f.getName();
if (items.size() > 0) {
buf.ln(_first()._nnHeader(f));
Iterator<E> i2 = items.values().iterator();
while (i2.hasNext()) {
E o = i2.next();
BoMap<E> m = (BoMap<E>)o.getBoMap(cn1);
if (m.size() > 0) {