UAX #11 East Asian Width-based approach is simpler, I think. It is used by Firefox to check the character is Chinese/Japanese or not. (c.f. 1940947 - Treat half-width Korean won currency sign (U+20A9 ₩) as Korean, not Chinese or Japanese) I released plugins for remark / markdown-it, which is based on this idea: GitHub - tats-u/markdown-cjk-friendly: Make CommonMark more friendly for Japanese/Chinese/Korean (CommonMark next specification draft)—plugins & patched packages Specifications dra...
