Many people have complained on Apple's iTunes forum about this problem.
iTunes does not make finding the answer easy. iTunes help does not recognize the word "rewind." Checking under keyboard shortcuts I found:
Move forward or backward within a song:
Option-Command-Right Arrow or Left Arrow
If the file is playing, the keystrokes will move 5 seconds in the chosen direction. It does not work if the file is paused.
Listening to an 8 hour audio book presents a problem. Using the slide bar to back up a few seconds is impossible because a few seconds is such a small portion of 8 hours. Any ideas?

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