`Info-prev-reference', instead of M-tab.
(define-key Info-mode-map " " 'Info-scroll-up)
(define-key Info-mode-map "\C-m" 'Info-follow-nearest-node)
(define-key Info-mode-map "\t" 'Info-next-reference)
- (define-key Info-mode-map "\e\t" 'Info-prev-reference)
+ (define-key Info-mode-map [(shift tab)] 'Info-prev-reference)
+ (define-key Info-mode-map [backtab] 'Info-prev-reference)
(define-key Info-mode-map "1" 'Info-nth-menu-item)
(define-key Info-mode-map "2" 'Info-nth-menu-item)
(define-key Info-mode-map "3" 'Info-nth-menu-item)