In order to continue its business in Japan, it must be able to produce digital publications with right-to-left and vertical writing
Modern Japanese doesn't use RTL text, it's just that the lines in vertical Japanese text are stacked RTL (whereas they are stacked LTR in Mongolian). Maybe just remove the 'right-to-left and' text ?
However, there are languages that are written with scripts that run overall RTL on horizontal lines, but actually exhibit bidirectional behaviour, such as Arabic, Persian, Urdu, Thaana, etc. This is likely to introduce significant technical challenges (such as page turning in the opposition direction), and so i think you should have a use case for it.
Also, many of the language-specific typographical differences rely on a knowledge of the language of the text to work (eg. a simple example being hyphenation), so it would be good to ensure that it's always possible to associate a single language with a range of content. Is that something that is worth mentioning in this document?
B.2 Internationalization https://w3c.github.io/dpub-pwp-ucr/#internationalization
Modern Japanese doesn't use RTL text, it's just that the lines in vertical Japanese text are stacked RTL (whereas they are stacked LTR in Mongolian). Maybe just remove the 'right-to-left and' text ?
However, there are languages that are written with scripts that run overall RTL on horizontal lines, but actually exhibit bidirectional behaviour, such as Arabic, Persian, Urdu, Thaana, etc. This is likely to introduce significant technical challenges (such as page turning in the opposition direction), and so i think you should have a use case for it.
Also, many of the language-specific typographical differences rely on a knowledge of the language of the text to work (eg. a simple example being hyphenation), so it would be good to ensure that it's always possible to associate a single language with a range of content. Is that something that is worth mentioning in this document?