List Match Marker

     (preprocessor) A match marker indicating a position that will
     successfully match a list of one or more arbitrarily complex
     expressions.  A list match marker marks a part of a command that is
     expected to consist of a list of programmer-supplied expressions.  A
     list match marker has the form <id,...>.  id associates a name with the
     match marker.  The name can be used in a result marker to specify how
     the matching source text is to be handled.