Céngkok (old orthography: chengkok) are patterns played by the elaborating instruments in the Javanese gamelan. They are melodic formula that lead to a sèlèh, following the rules of the pathet of the piece. The most elaborate cengkok repertoire is that of the gendér barung. The gambang and siter, on the other hand, do not have such formalized sets of cengkok, and therefore may vary more from performer to performer.