For the lower face, AUs 9 (nose wrinkler), 10 (upper lip raiser) and 17 (chin raiser) are not addressed in
ToonFace. Ml represents the motions involving AUs 15 (vertical lip corner depressor), 25 (vertical lips part) and 26
(jaw drop). No differentiation is made between AU 26 and AU 27 (vertical mouth stretch), since the jaw is not
modeled separately from the lower lip. Ml and Mr together can approximate the AUs 20 (horizontal lip stretcher)
and 14 (dimpler), as well as what Ekman and Friesen [1978] call ÒobliqueÓ actionsÑpulling out and up diagonally
on the corners of the mouth.