The 1950s version is as follows: Several other notes: A single stroke can be represented in more than one corner, as is the case with many curly strokes. (e.g. the code for 乙 is 1771) If the character is fenced by , (门), or , the lower corners are used to denote what is inside the radical, instead of 00 for 囗 or 22 for the others. (e.g. the code for 回 is 6060) There have been scores, maybe hundreds, of such numerical and alpha-numerical systems proposed or popularized (such as Lin Yutang's "Instant Index", Trindex, Head-tail, Wang An's Sanjiahaoma, Halpern); some Chinese refer to these generically as sijiaohaoma (after the original pamphlet) though this is not correct. Versions Over time, the Four-Corner Method has gone through some changes. First Version The first (revised) version was published in Shanghai in 1928. It was quickly adopted and popularized as a method for (among other things): Arranging and indexing Chinese characters in dictionaries Indexing Chinese classical and modern books, libraries, hospital and police records Chinese typewriters Military code making (for handling the characters quickly) The Wang Yun-wu Da Cidian of 1928 was remarkable for its time, and although the pronunciations were very much in line with today's Standard Chinese, the lack of a phonetic index diminished its overall usefulness. The northern Mandarin pronunciations were given in Gwoyeu Romatzyh, a romanization system devised by linguist Zhao Yuanren, as well as in Mandarin Phonetic System (MPS or Bopomofo) characters with a dotted corner for tone. It also delineated parts of speech, and all compounds were listed by the four-corner method as well. The famed lexicographer and editor of Ciyuan, Lu Erkui, as well as other lexicographers, became early proponents of the Four-Corner Method. By 1931, it was used extensively by the Commercial Press to index virtually all classical reference works and collections of China, such as the Pei Wen Yun Fu and Siku Quanshu, as well as many modern ones. Hospital, personnel and police records were organized just like the biographical indexes and dynastic histories of former times. For a while (Nash, Trindex, 1930), it seemed that use of the 214 Kangxi radicals, introduced during the Qing Dynasty, was being replaced by the Four-Corner Method. Internationally, Harvard and other universities were using the method for their book collections, and the KMT government in Nanjing seemed to have selected this numerical system as its standard.