Tone patterns are common constraints in classical Chinese poetry

Chinese poetry

Chinese poetry is poetry written, spoken, or chanted in the Chinese language, which includes various versions of Chinese language, including Classical Chinese, Standard Chinese, Mandarin Chinese, Cantonese, Yue Chinese, as well as many other historical and vernacular varieties of the Chinese language...

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The four tones

Four tones

The four tones of Chinese phonology are four traditional tone-classes of words derived from the four phonemic tones of Middle Chinese. They are even level , rising , going departing , and entering checked .-Names:In Middle Chinese, each of the tone names carries the tone it identifies: 平 even ,...

 of Middle Chinese—level (平), rising (上), departing (去), and entering (入) tones—are categorized into level (平) tones and oblique (仄) tones. All level tones are level. All other tones are oblique. If tone patterns are used in poetry, the pattern in which level and oblique tones occur in one line is often the inverse of a that of line next to it. For example, in the poem 春望 (pinyin

Pinyin

Pinyin is the official system to transcribe Chinese characters into the Roman alphabet in China, Malaysia, Singapore and Taiwan. It is also often used to teach Mandarin Chinese and spell Chinese names in foreign publications and used as an input method to enter Chinese characters into...

: chūn wàng, Spring View) by Du Fu

Du Fu

Du Fu was a prominent Chinese poet of the Tang Dynasty.Along with Li Bai , he is frequently called the greatest of the Chinese poets. His greatest ambition was to serve his country as a successful civil servant, but he proved unable to make the necessary accommodations...

, the tone pattern of the first line is 仄仄平平仄, while that of the second line is 平平仄仄平:

國(仄)
破(仄)
山(平)
河(平)
在(仄)

城(平)
春(平)
草(仄)
木(仄)
深(平)