(SIP) The third plane (plane 2) defined in
Unicode/
ISO 10646, designed to hold all the ideographs
descended from Chinese writing (mainly found in Vietnamese,
Korean, Japanese and Chinese) that aren't found in the
Basic Multilingual Plane. The BMP was supposed to hold all
ideographs in modern use; unfortunately, many Chinese dialects
(like Cantonese and Hong Kong Chinese) were overlooked; to
write these, characters from the SIP are necessary. This is
one reason even non-academic software must support characters
outside the BMP.
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