code: void addDelta(TableKelp db, int offset, int length)
    {
      if (_delta == null) {
        _delta = new int[2 * db.getDeltaMax()];
      }
      
      _delta[_deltaTail++] = offset;
      _delta[_deltaTail++] = length;
    }
docs: Adds a delta record to the leaf stub.