code: protected AbcTune parseAbcHeader(AbcNode abcHeader) {
  		// X: number
  		AbcNode digits = abcHeader.getChild(FieldNumber+"/"+DIGITS);
  		if (digits != null)
  			m_tune.setReferenceNumber(Integer.parseInt(digits.getValue()));
  		// T: titles
  		parseTitleFields(abcHeader.getChild(TitleFields));
  		parseOtherFields(abcHeader);
  		//TODO getChildsInAllGeneration(Xcommand)
  		parseFieldKey(abcHeader.getChild(FieldKey));
  		return m_tune;
  	}
docs: If you call directly parseAbcHeader, be sure to
  call {@link #initNewTune()} and listener notifiers.
  <p>
  See {@link TuneParser#parseHeader0(AbcNode)} for example.