Restricted Match Marker

     (preprocessor) A match marker indicating a position that will
     successfully match one or more specified keywords.  A restricted match
     marker marks a part of a command that is expected to be a keyword.  A
     restricted match marker has the form <id: wordList> where wordList is a
     list of one or more keywords.  Source text is successfully matched only
     if it matches one of the keywords (or is an acceptable abbreviation).
     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.