if (validating) {  ExternalIds notation = doctype.getNotation(notationName); if (notation != null) error("duplicate notation name", notationName); }
  private void readNotationDecl(boolean inExternalSubset)    throws IOException, XMLStreamException  {    requireWhitespace();    String notationName = readNmtoken(true);    if (notationName.indexOf(':') != -1)      error("illegal character ':' in notation name", notationName);    requireWhitespace();    ExternalIds ids = readExternalIds(true, false);    ids.notationName = notationName;    doctype.addNotationDecl(notationName, ids, inExternalSubset);    skipWhitespace();    require('>');  }