Existing character set standards such as the Japanese JIS X 0208 (encoded by Shift JIS) defined unification criteria, meaning rules for determining when a variant Chinese character is to be considered a handwriting/font difference (and thus unified), versus a spelling difference (to be encoded separately). Unicode's character model for CJK characters was based on the unification criteria used by JIS X 0208, as well as those developed by the Association for a Common Chinese Code in China.
Existing character set standards such as the Japanese JIS X 0208 (encoded by Shift JIS) defined unification criteria meaning rules for determining when a variant Chinese character is to be considered a handwriting/font difference (and thus unified) versus a spelling difference (to be encoded separately) Unicode's character model for CJK characters was based on the unification criteria used by JIS X 0208 as well as those developed by the Association for a Common Chinese Code in China