This directory contains grammar files in Bison and Wisent, used to
generate the parser data in the lisp/semantic/bovine/ and
lisp/semantic/wisent/ directories.  You can run the parser generators
with

emacs -batch -Q -l semantic/bovine/grammar -f bovine-make-parsers
emacs -batch -Q -l semantic/wisent/grammar -f wisent-make-parsers

Currently, the parser files in lisp/ are not generated directly from
these grammar files when making Emacs.  This state of affairs, and the
contents of this directory, will change in a future version of Emacs.