Sheng - perogative of the leading actor, usually a male character, a scholar, a statesman, a warrior patriot and the like.
Tau - plays all the women's roles. Atleast 6 principal characters are played by the female impersonator who has taken over the role after woman were banned from the chinese stage as they were looked down upon as courtsen.
Ching - roles usually assigned the roles of brave warriors, bandits, crafty and evil ministers, upright judges, loyal statesmen at times god-like and supernatural beings.
They must have broad faces and forehead suitable for make-up patters suggestive of his behavior.
Chau - clown/jester but not necessarily a fool and may do serious or evil characters, recognized for white patch around his eyes and nose.