code: Rule LyricsIfield() {
  		return ZeroOrMore(FirstOfS(LyricsSyllableBreak(), LyricsNextBar(),
  				LyricsHold(), LyricsSkipNote(), LyricsNbsp(), LyricsDash(),
  				LyricsSyllableIfield()))
  			.label(LyricsIfield);
  	}
docs: lyrics-ifield ::= *(lyrics-char-ifield / lyrics-syllable-break / lyrics-next-bar
  / lyrics-hold / lyrics-skip-note / lyrics-nbsp / lyrics-dash / tex-escape)