is ck a digraph
In several European writing systems, including the English one, the doubling of the letter â¨câ© or â¨kâ© is represented as the heterogeneous digraph â¨ckâ© instead of â¨ccâ© or â¨kkâ© respectively. In native German words, the doubling of â¨zâ©, which corresponds to /ts/, is replaced by the digraph â¨tzâ©.