Editing Shift JIS (section)

=== Shift_JISx0213 and Shift_JIS-2004 === <!-- [[Shift_JIS-2004]] redirects here -->
{{infobox character encoding
| name = Shift_JIS-2004
| mime = 
| alias = Shift_JISx0213
| standard = JIS X 0213
| lang = [[Japanese language|Japanese]], [[Ainu language|Ainu]], [[English language|English]], [[Russian language|Russian]]
| status =
| extends = Shift_JIS (1997),<br/>[[JIS X 0201]] (8-bit)
| encodes = [[JIS X 0213]]
| prev = Shift_JIS (1997)
| next = 
}}

The newer [[JIS X 0213]] standard defines an extended variant of Shift_JIS referred to as '''Shift_JISx0213''' (in a previous version of the standard) or '''Shift_JIS-2004'''. It is a superset of standard Shift JIS.<ref name="x0213org">{{cite web | url=http://x0213.org/codetable/index.en.html | title=JIS X 0213 Code Mapping Tables | publisher=x0213.org}}</ref>

In order to represent the allocated rows on both planes of JIS X 0213, Shift_JIS-2004 uses the following method of mapping codepoints.<ref>{{cite web | url=http://www.asahi-net.or.jp/~wq6k-yn/code/enc-x0213.html#sjis-2004 | title=JIS X 0213の代表的な符号化方式 § Shift_JIS-2004 | language=ja}} Hexadecimal numbers in the source have been converted to decimal for display.</ref>

:<math>s_1 = \begin{cases} \left \lfloor \frac{k + 257}{2} \right \rfloor & \mbox{if } m = 1 \mbox{ and } 1 \le k \le 62 \\
                           \left \lfloor \frac{k + 385}{2} \right \rfloor & \mbox{if } m = 1 \mbox{ and } 63 \le k \le 94 \\
                           \left \lfloor \frac{k + 479}{2} \right \rfloor - \left \lfloor \frac{k}{8} \right \rfloor \times 3 & \mbox{if } m = 2 \mbox{ and } k = 1, 3, 4, 5, 8, 12, 13, 14, 15 \\
                           \left \lfloor \frac{k + 411}{2} \right \rfloor & \mbox{if } m = 2 \mbox{ and } 78 \le k \le 94             \end{cases}</math>
:<math>s_2 = \begin{cases} t + 63 & \mbox{if } k \mbox{ is odd and } 1 \le t \le 63 \\
                           t + 64 & \mbox{if } k \mbox{ is odd and } 64 \le t \le 94 \\
                           t + 158 & \mbox{if } k \mbox{ is even }
             \end{cases}</math>
In the above, <math>s_1 s_2</math> is a two-byte Shift_JIS-2004 sequence, <math>m</math> is the {{Nihongo|plane|面|men|surface}} number (1 or 2), <math>k</math> is the {{Nihongo|row|区|ku|ward}} number (1-94) and <math>t</math> is the {{Nihongo|cell|点|ten|point}} number (1-94). The ''ku'' and ''ten'' numbers are equivalent to <math>j_1 - 32</math> and <math>j_2 - 32</math> respectively, where <math>j_1 j_2</math> is a two-byte JIS sequence referencing a given plane.

The same set of characters can be represented by [[EUC-JIS-2004]], the EUC-JP based counterpart.

Some of the additions collide with popular Shift JIS extensions, including Windows codepage 932 which is used in web standards (see [[#Windows-932 / Windows-31J|above]]). For example, compare plane 1 row 89 in {{nowrap|JIS X 0213}} (beginning 硃, 硎, 硏...)<ref>{{cite iso-ir |number=233 |title=Japanese Graphic Character Set for Information Interchange, Plane 1 |sponsor=Japanese Industrial Standards Committee |sponsor-link=Japanese Industrial Standards Committee |date=2004-04-13}}</ref> to row 89 in the JIS X 0208 variant defined in web standards (beginning 纊, 褜, 鍈...).<ref>{{cite web | url=https://encoding.spec.whatwg.org/jis0208.html | title=Index jis0208 visualization | publisher=WHATWG | work=Encoding Standard}}</ref> In addition, some of the characters map to Unicode characters beyond the BMP.