Northumbrian pipers with the usual F Chanter know that the sound they produce is not the sound of the written note but the note one tone below. For guitar chords this is taken care of in the books as there is a separate series of chord symbols in the sounding key of the music.
However, if you are playing duets with a player of a non-transposing instrument you usually have to write all of the music out in the necessary key. Non-transposing instruments include violin, flute, recorder, etc.
The problem is solved in the "transposed inserts" - they contain exactly the same material as the main book but transposed down one tone. They are cheaper than the main books as they come without a card cover.