Imperial units commonly used units for length are (li), (tseung/cheung), (tsek/chek), (tsun/chun), (fen/fan) in descending scale order. These units are now rarely used in daily life, the imperial and metric systems being preferred. The imperial equivalents are written with the same basic Chinese characters as the Chinese system. In order to distinguish between the units of the two systems, the units can be prefixed with "Ying" () for the Imperial system and "Wa" () for the Chinese system. In writing, derived characters are often used, with an additional (mouth) radical to the left of the original Chinese character, for writing imperial units.
Imperial pigeon Imperial pigeon Ducula is a major genus of the pigeon family Columbidae, collectively known as imperial pigeons. They are large to very large pigeons with a heavy build and medium to long tails. They are arboreal, feed mainly on fruit and are closely related to the other genus of fruit-eating doves, "Ptilinopus". Both genera display brightly coloured plumage, predominantly green, often with contrasting under-parts of purple, orange or red. Some "Ducula" have prominently swollen ceres. They have large gapes and swallow seeds whole, playing an important role in seed dispersal. Imperial pigeons are found in forests of southern Asia, New