code: Rule FieldTempo() {
  		return Sequence(
  				String("Q:"),
  				ZeroOrMore(WSP()).suppressNode(),
  				FirstOfS(Tempo(), TempoText()),
  				ZeroOrMore(WSP()).suppressNode(),
  				OptionalS(FirstOfS(Tempo(), TempoText())),
  				HeaderEol()).label(FieldTempo);
  	}
docs: field-tempo ::= %x51.3A *WSP tempo header-eol<p>
  <tt>Q:</tt>