This appears to be
a bizarre way of identifying chess pieces, in the starting position of the game.
Rooks are called "Tower"s, and knights are called "Horse"s. Then each piece is given four letters: the last letter of its name, the first letter of its name, the last letter of its color, and the first letter of the color of its square.
the pieces are read out in diagonal lines, starting from the top left:
Number 8 is "GKKW", for the black³ k²ing¹ sitting on a w⁴hite square. Perhaps it was removed because "GK" is a unique string in the given pieces, and that would make it easier to identify the pattern that the pieces were taken in?
[Also, a minor inconsistency:]
It appears that after piece 15, all the pawns have their first two characters swapped. I believe this to be a mistake, but there may be something I haven't figured out yet.