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The word list used by the UNIX spelling checker, SPELL, was developed from many sources over several years. As the spelling checker may be used on minicomputers, it is important to make the list as compact as possible. Stripping prefixes and suffixes reduces the list below one third of its original size, hashing discards 60 percent of the bits that remain, and data compression halves it once again. This paper tells how the spelling checker works, how the words were chosen, how the spelling checker was used to improve itself, and how the (reduced) list of 30000 English words was squeezed into 26000 16-bit machine words.
Marie McIlroy (Fri,) studied this question.