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 al., and followed here. Four species of imperial pigeon are found in Philippines and Sulawesi. All have a distinct pale band across the centre of the tail, and a rich green or purple dorsum. This grouping shares characteristics and distribution with "Ptilinopus", and forms a link between the genera. The pink-belled ("D. poliocephala") and the white-bellied ("D. forsteni") imperial pigeon are similar and allopatric species. The Mindoro ("D. mindorensis") and the grey-headed ("D. radiata") imperial pigeons differ in size but are otherwise similar. The spotted imperial pigeon ("D. carola") is sympatric to "D. poliocephala", and though smaller, short tailed and