code: public String getNamespace(int ExpandedNameID)
    {
      String namespace = m_extendedTypes[ExpandedNameID].getNamespace();
      return (namespace.equals("") ? null : namespace);
    }
docs: Given an expanded-name ID, return the namespace URI part.
  
  @param ExpandedNameID an ID that represents an expanded-name.
  @return String URI value of this node's namespace, or null if no
  namespace was resolved.