How is it related to Unicode / ISO/IEC 10646?
Almost all characters in JIS X0213 have corresponding characters in Unicode / ISO/IEC 10646. Only a few non-Kanji characters are represented by composite sequences in Unicode / ISO/IEC 10646. Kanji characters are mapped to one of the blocks of CJK Unified Ideographs, CJK Compatibility Ideographs, CJK Unified Ideographs Extension A, or CJK Unified Ideographs Extension B in Unicode 4.0 (or later versions) and corresponding versions of ISO/IEC 10646; or are mapped to CJK Compatibility Ideographs.