Thank you, Wolfgang, for that. But it still does not handle the after key, as I had in my example, and which works in a processor for index entries. Is there no way to do this?\defineprocessor [bodypart] [style=bold]4. August 2015 00:18Should processors work with references? I would think that they should, but the following fails. (My backmatter page numbers need to be marked to distinguish them from bodymatter pages. I can automate applying a processor based on the location for index register entries, but not for references.)
\defineprocessor [backpart] [style=italic]
\defineconversionset[bodypart:pagenumber][][bodypart->n]
\defineconversionset[backpart:pagenumber][][backpart->n]
\setupheadertexts[{\convertedcounter[userpage][numberconversionset=number]}]
\starttext
\startbodymatter
\chapter[sec:knuth]{Knuth}
\at{page}[sec:knuth]\par
\at{page}[sec:zapf]
\stopbodymatter
\startbackmatter
\chapter[sec:zapf]{Zapf}
\at{page}[sec:knuth]\par
\at{page}[sec:zapf]
\stopbackmatter
\stoptext
Wolfgang