I'm typesetting some XML text with comments in and for the working version the comments are to go in the margin. For the final version the comments are simply to be ignored. In the end result there is a noticeably larger space between the words where the comma had been. Apparently more than one space is reaching TeX's stomach, though it's beyond me to work out how. I suppose I need a more sophisticated \gobble definition than the simple TeXbook one, yes? ----file minimal.tex %now we will map XML arguments to context ones. \defineXMLargument [title] \title \defineXMLargument [footnote] \footnote \defineXMLargument [section] \section % et cetera.... % this definition for drafts where comments are printed %in the margin %\defineXMLargument [comment] \inmargin %this definition for the final version where the % remaining comments are ignored \def\gobble#1{} \defineXMLargument [comment] \gobble \starttext \processXMLfilegrouped {sample.xml} \stoptext --- file sample.xml <article> <title>Nonsense</title> <text> <section>A section </section> Makes complicated pages by starting with simple individual characters and putting them together in larger units, and putting these together <comment>what does he mean here, putting these together???</comment> in still larger units, and so on. Conceptually, it's a big paste-up job.<footnote>From The TeXbook.</footnote> </text> </article>