module XML {

enum attribute_kind { CDATA, IDref, ID, IDrefs };

enum element_kind { TAG, PCDATA };


union attribute_type switch (attribute_kind)
{  case CDATA:  string       value;
   case IDref:  string       id_ref;
   case IDrefs: list<string> id_refs;
   case ID:     string       xid;
};


struct attribute_binding
{  string         name;
   attribute_type value;
};


struct node_type {
   string		   name;
   list<attribute_binding> attributes;
   list<XML_element>	   content;
};


union element_type switch (element_kind)
{  case TAG:    node_type tag;
   case PCDATA: string    data;
};


class XML_element
( extent Elements )
{  attribute element_type xml_element;
   string data();
   string tag();
};


class XML_document
( extent Documents key name )
{  attribute string            name;
   attribute list<XML_element> content;
};

};