Peking opera features four main role types, "sheng" (gentlemen), "dan" (women), "jing" (rough men), and "chou" (clowns). Performing troupes often have several of each variety, as well as numerous secondary and tertiary performers. With their elaborate and colorful costumes, performers are the only focal points on Peking opera's characteristically sparse stage. They use the skills of speech, song, dance and combat in movements that are symbolic and suggestive, rather than realistic. Above all else, the skill of performers is evaluated according to the beauty of their movements. Performers also adhere to a variety of stylistic conventions that help audiences navigate the plot of the production. The layers of meaning within each movement must be expressed in time with music. The music of Peking opera can be divided into the () and () styles. Melodies include arias, fixed-tune melodies and percussion patterns. The repertoire of Peking opera includes over 1,400 works, which are based on Chinese history, folklore and, increasingly, contemporary life.