In Cued Speech, placements represent vowel phonemes. In some adaptations, hand movements have been added to further clarify vowels. In American English, there are two movement cues: side-forward and side-down.
It may be worth noting that diphthongs are not movement cues. Cues for diphthongs comprise two vowel locations with a glide between these two locations. For example, the salient portions of the side-throat diphthong is the side placement and the throat placement. The movement from the side to the throat that occurs when cueing the diphthong is simply a transition between the placements and carries no phonemic value.
In the Inventory of Cues available for adaptations to foreign languages and dialects, the rotation is a new and somewhat unique addition. In previous adaptations, the cueing hand is always oriented so that the back of the hand faces the receiver. Further research is needed to determine how these cuers will cope with frequent twisting of the wrist that will be required when fluency develops.
In Portuguese, a quarter rotation of the wrist as the hand contacts the cheekbone (which changes the orientation of the palm so the thumb rotates toward the ear) is used to represent the vowel phoneme in the word sim (yes).
In the Cued Speech adaptation for Marathi, a half-rotation of certain handshapes (so that the palm face forward and the thumb points down) is used to convey different phonemes. This marks a significant difference for the Marathi adaptation in that it is the only adaptation that uses a palm orientation to differentiate handshapes.