+Bison requires GNU m4 1.4.6 or later. See:
+
+ ftp://ftp.gnu.org/gnu/m4/m4-1.4.6.tar.gz
+
+** Internationalization
+Bison supports two catalogues: one for Bison itself (i.e., for the
+maintainer-side parser generation), and one for the generated parsers
+(i.e., for the user-side parser execution). The requirements between
+both differ: bison needs ngettext, the generated parsers do not. To
+simplify the build system, neither are installed if ngettext is not
+supported, even if generated parsers could have been localized. See
+http://lists.gnu.org/archive/html/bug-bison/2009-08/msg00006.html for
+more details.
+
+* Questions