https://gist.github.com/kirstenfrank/218c36a1938055d0f4e4sample codebook.
It's very similar to a Statistical Analysis Plan, actually.
Setup, there is a dogwalking business. It wants to analyze its work.
Raw data is: name of dog, address of owner, time walked, date walked, size of dog (small, medium, or large), health of dog (well or sick) on that date and time, comments, and pay.
The business wants to assign ID# to the dogs, and codewords to the address to make this data anonymous. There isn't anything to do to the comments--since free text is all over the place.