The epilogue section contains arbitrary Emacs Lisp code which is copied verbatim to the end of the parser file, just as the prologue is copied to the beginning. This is the most convenient place to put anything that you want to have in the parser file.
For example, it could be convenient to put the definition of the lexer in the epilogue, particularly if it includes lexical rules auto-generated from declarations in the grammar.
If the epilogue section is empty, you may omit the
that separates it from the grammar rules.
;;; my-grammar.by ends here
At the end of the grammar. It will not be copied to the parser file to avoid confusion with the Emacs Lisp library own footer.