code: public void removeElementAt(int i)
    {
  
      if (!m_mutable)
        throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESETDTM_NOT_MUTABLE, null)); //"This NodeSetDTM is not mutable!");
  
      super.removeElementAt(i);
    }
docs: Deletes the component at the specified index. Each component in
  this vector with an index greater or equal to the specified
  index is shifted downward to have an index one smaller than
  the value it had previously.
  
  @param i The index of the node to be removed.
  @throws RuntimeException thrown if this NodeSetDTM is not of
  a mutable type.