Blockify Result Marker

     (preprocessor) A result marker of the form <{id}>.  id must correspond
     to the name of a match marker.  A blockify result marker specifies that
     the corresponding source text is to be blockified.  If the matched
     source text is a list of expressions, each expression in the list is
     individually blockified.  If no source text matched the corresponding
     match marker, an empty result is produced.