code: private final int appendNode(int w0, int w1, int w2, int w3)
          {
                  // A decent compiler may inline this.
                  int slotnumber = nodes.appendSlot(w0, w1, w2, w3);
  
                  if (DEBUG) System.out.println(slotnumber+": "+w0+" "+w1+" "+w2+" "+w3);
  
                  if (previousSiblingWasParent)
                          nodes.writeEntry(previousSibling,2,slotnumber);
  
                  previousSiblingWasParent = false;	// Set the default; endElement overrides
  
                  return slotnumber;
          }
docs: Wrapper for ChunkedIntArray.append, to automatically update the
  previous sibling's "next" reference (if necessary) and periodically
  wake a reader who may have encountered incomplete data and entered
  a wait state.
  @param w0 int As in ChunkedIntArray.append
  @param w1 int As in ChunkedIntArray.append
  @param w2 int As in ChunkedIntArray.append
  @param w3 int As in ChunkedIntArray.append
  @return int As in ChunkedIntArray.append
  @see ChunkedIntArray.append