+* Undefined token
+ The undefined token was systematically mapped to 2 which prevented
+ the use of 2 from the user. This is no longer the case.
+
+* Undefined token
+ If yylex returned a code out of range, yyparse could die. This is
+ no longer the case.
+
+* Error token
+ According to POSIX, the error token should be numbered as 256.
+ Bison extends this requirement by making it a preference: *if* the
+ user specified that one of her tokens is numbered 256, then error
+ will be mapped onto another number.
+
+* Large grammars
+ Are now supported (large token numbers, large grammar size (= sum of
+ the LHS and RHS lengths).
+
+* The initial rule is explicit.
+ Bison used to play hacks with the initial rule, which the user does
+ not write. It is now explicit, and visible in the reports and
+ graphs as rule 0.
+
+* Useless rules are actually removed.
+ Before, Bison reported the useless rules, but, although not used,
+ included them in the parsers.
+
+* False `Token not used' report fixed.
+ On a grammar such as
+
+ %token useless useful
+ %%
+ exp: '0' %prec useful;
+
+ where a token was used to set the precedence of the last rule,
+ bison reported both `useful' and `useless' as useless tokens.
+
+* Revert the C++ namespace changes introduced in 1.31, as they caused too
+ many portability hassles.
+