anchor.diff:          (digits   (advance (token tok-numero)))
           (dot      (advance (token tok-nombre))
                     (shift nombre-mantissa))
  -        ("E"      (advance :error-on-eof "IL MANQUE L'EXPOSANT APRES 'E'")
  +        (exponent (advance :error-on-eof "IL MANQUE L'EXPOSANT APRES 'E'")
                     (shift nombre-exponent))
           ((concat spaces star)
            (shift maybe-commentaire) (produce (token tok-numero)))
  
positive.code:         (digits   (advance (token tok-numero)))
          (dot      (advance (token tok-nombre))
                    (shift nombre-mantissa))
          ("E"      (advance :error-on-eof "IL MANQUE L'EXPOSANT APRES 'E'")
                    (shift nombre-exponent))
          ((concat spaces star specials specials-2 signs)
           (shift not-commentaire) (produce (token tok-numero)))
  
negative.code:        
         (nombre-mantissa ; 6
          (digits   (advance (token tok-nombre)))
          (exponent (advance :not-eof  "IL MANQUE L'EXPOSANT APRES 'E'")
                    (shift nombre-exponent))
          ((concat spaces specials specials-2 dot star signs)
           (shift not-commentaire) (produce (token tok-nombre)))
  