code: private void rightMove(
      int           ix)
    {
      for (int j = rightMostIndex()-1; j >= ix; j--)
        _nodeKey[j+1] = _nodeKey[j];
    }
docs: Open up a slot for a new key by shifting keys right to make room
  and overlaying the right-most key.
  
  <p>We are inserting a new key into a node that is currently full.
  We open up the correct slot for the new key by shifting all other
  keys right, overlaying the right-most key.</p>