About page 726, Colonel Robin Zacharias is communicating to a friend, Al Wallace, in the cell next to his using an old POW communications code, a series of taps that match up to letters in a simple layout, 5 across 5 down.

The problem is the code given in the book is missing the letter K. It's supposed to be in there, because a few sentences after the code, Al replies to a query from Robin "MAKIN IT"