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Because the current normalization strategy is very ASCII / Latin-centric, languages such as CJK ones are entirely excluded from having valid characters in page slugs, which makes it difficult to create native pages. As part of WJ-792, Wikijump added additional characters which are supported by normal form, while still retaining the general properties of normalization.
See (TODO) Wikijump Normal Form for more information on internationalized normal form.
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