code: Rule IfieldTranscription() {
  		return Sequence(String("[Z:"),
  				ZeroOrMore(WSP()).suppressNode(),
  				TexTextIfield(),
  				String("]"))
  			.label(IfieldTranscription);
  	}
docs: ifield-transcription ::= %5B.%5A.%3A *WSP tex-text-ifield %5D<p>
  <tt>[Z:..]</tt>