Sending results up the parse tree
The reserved word, RESULTS, is used to send data from a lower level of the parse tree up to a higher level:
book ::= Book_ST title:t author:a date:d isbn:i publisher:p Book_ET ;
title ::= Title_ST PCDATA:title Title_ET {: RESULT = "<TD>" + title + "<TD>"; :}
The RESULT from the title rule gets sent up to the book rule.