-@code{YYDEBUG} when you compile the parser. You could use
-@samp{-DYYDEBUG=1} as a compiler option or you could put @samp{#define
-YYDEBUG 1} in the C declarations section of the grammar file
-(@pxref{C Declarations, ,The C Declarations Section}). Alternatively, use the @samp{-t} option when
-you run Bison (@pxref{Invocation, ,Invoking Bison}). We always define @code{YYDEBUG} so that
-debugging is always possible.
+@code{YYDEBUG} when you compile the parser. You could use @samp{-DYYDEBUG=1}
+as a compiler option or you could put @samp{#define YYDEBUG 1} in the prologue
+of the grammar file (@pxref{Prologue, , The Prologue}). Alternatively, use the
+@samp{-t} option when you run Bison (@pxref{Invocation, ,Invoking Bison}).
+We always define @code{YYDEBUG} so that debugging is always possible.