There are three distinct ways to rotate your forearm (jap. "kote"):
Kotegaeshi = supinating rotation with palm inwards.
Kotehineri aka Sankyo = pronating rotation with palm outwards.
Kotemawashi aka Nikyo = pronating rotation combined with flexion of the wrist ("hook").
The most important wrist (jap. "tekubi") positions are the "hook" and the "hand-blade" (jap. "te-gatana").
Yang Cheng-fu in c. 1934 in the "single whip" posture (Essence and Applications of Taijiquan, orig. Taijiquan Tiyong Quanshu). Left hand is palm outwards, right hand forms a hook.
Te-gatana (jap. 手刀, "hand-blade") explained according to Yoshigasaki (2020):
Put your forearm on a table so that it does not move (photo 1).
Your hand can move either towards little finger or thumb. Move you hand maximally towards your thumb (photo 2).
Turn the arm without moving the elbow. Now you have a correct form of Tegatana (photo 3).
Kenjiro Yoshigasaki, 25th of March 2020, https://toitsu.dk/lectures_from_doshu/aiki_taiso.html
Normal wrist and forearm movements are a) flexion-extension, b) radioulnar deviation, c) rotation.