language of China, has four lexically contrastive tones, and the digits 1, 2, 3, and 4 are assigned to four tones. Syllables can sometimes be toneless and are described as having a neutral tone, typically indicated by omitting tone markings. Chinese varieties are traditionally described in terms of four tonal categories ping ('level'), shang ('rising'), qu ('exiting'), ru ('entering'), based on the traditional analysis of Middle Chinese (see Four tones); note that these are not at all the same as the four tones of modern standard Mandarin Chinese. Depending on the dialect, each of these categories may then be divided into two tones, typically called yin and yang. Typically, syllables carrying the ru tones are closed by voiceless stops in Chinese varieties that have such coda(s) so in such dialects, ru is not a tonal category in the sense used by Western linguistics but rather a category of syllable structures. Chinese phonologists perceived these checked syllables as having concomitant short tones, justifying them as a tonal category. In Middle Chinese, when the tonal categories were established, the shang and qu tones also had characteristic final obstruents with concomitant tonic differences whereas syllables bearing the ping tone ended in a simple sonorant. An alternative to using the Chinese category names is assigning to each category a digit ranging from 1 to 8, sometimes higher for some Southern Chinese dialects with additional tone splits. Syllables belonging to the same tone category differ drastically in actual phonetic tone across the varieties of Chinese even among dialects of the same group. For example, the yin ping tone is a high level tone in Beijing Mandarin Chinese but a low level tone in Tianjin Mandarin Chinese. More iconic systems use tone numbers or an equivalent set of graphic pictograms known as "Chao tone letters." These divide the pitch into five levels, with the lowest being assigned the value 1 and the highest the value 5. (This is the opposite of equivalent systems in Africa and the Americas.) The variation in pitch of a tone contour is notated as a string of two or three numbers. For instance, the four Mandarin Chinese tones are transcribed as follows (the tone letters will not display properly without a compatible font installed): A mid-level tone would be indicated by /33/, a low level tone /11/, etc. The doubling of the number is commonly used with level tones to distinguish