Coal is the only one on the list of chores that is not in the book.
What does TBD mean for HINT?
ASK NELDOR ABOUT OLIVER. (He's on the list.)
'TBD' means 'To Be Determined'. That was a placeholder until I got around to implementing a hint system. I've replaced that message in version 0.0.3, but haven't implemented a full-blown hint system yet.