Harrington on Hold em Vol 3: Questions

[Thailog]

I've just worked my way through Vol 3. '390' - better than I expected.

Can anyone make any sense of the "Categorizing Your Errors" section of the book?

References to 1c or 39b are easy enough figure out, but what question/answer is referred to by 8Ac, 15Dc, or 11Aa?

I'd appreciate any suggestions on breaking the code.