code: Rule XcomSep() {
  		return Sequence(String("sep"),
  				ZeroOrMoreS(SequenceS(WSPS(), XcomNumber(), XcomUnit()))
  			).label(XcomSep);
  	}
docs: xcom-sep ::= "sep" [3(1*WSP xcom-number xcom-unit)]
  <p>
  space-above, space-below, width