Oryoki is tableware, as used by an individual ascetic of the Zen sect of Buddhism. The Sanskrit word for "oryoki" is "patra." Patra's transliteration in Japanese is "hattara." Oryoki is also called "hatsuu" or "teppatsu" in Japanese.
The term "oryoki" is mainly used by the Soto Zen sect, while in the Rinzai Zen sect it is called "jihatsu" (written in Chinese characters as "持鉢" (or "自鉢" in Rinzai Zen's Obaku school)).
Oryoki comprises a nest of five (or three in Obaku school) bowls, to which various kinds of tableware attach, such as fukusa (napkin), hizakake (lap robe), jokin (lap cloth), suiban (water board), hattan (place mat), hashi (a pair of chopsticks), saji (spoon) and setsu (spatula).
Principally, oryoki should be iron or earthen instead of wooden, but lacquered ware is deemed to be iron so generally black-lacquered ware is used. The vermilion-lacquered ware is mainly used in a Buddhist ritual but not in daily life.
The table manners are rigid in regard to oryoki, and they're part of the important ascetic practices in the Zen sect. Rice porridge should be served in the largest bowl, and soup, kosai (or called tsukemono (Japanese pickled vegetables)), fukusai (side dish) should each be served in a specific bowl. Animal foodstuffs and flavorings are forbidden.
The largest bowl is deemed to be the skull of Sakyamuni (the founder of Buddhism), and the bowl is called "zuhatsu." Zuhatsu should be handled carefully, so rough handling, such as putting the bowl to one's lips, is strictly forbidden. In addition to a meal, zuhatsu is used as a bowl in which to receive offerings when an ascetic is in takuhatsu (mendicancy).