Halfwidth and fullwidth forms: Difference between revisions

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==Rationale==
{{More citations needed section|date=April 2021}}
[[File:Alternative names of JIS X 0213.svg|thumb|Characters which appear in both [[JIS X 0201]] (single byte) and [[JIS X 0208]] / [[JIS X 0213]] (double byte) have both a halfwidth and a fullwidth form in [[Shift JIS]].|class=skin-invert]]
In the days of [[text mode]] computing, Western characters were normally laid out in a grid on the screen, often 80 columns by 24 or 25 lines. Each character was displayed as a small [[dot matrix]], often about 8 [[pixel]]s wide, and aan [[SBCS]] (single-byte character set) was generally used to encode characters of Western languages.
 
For aesthetic reasons and readability, it is preferable for [[Chinese characters]] to be approximately square-shaped, therefore twice as wide as these fixed-width SBCS characters. As these were typically encoded in a [[double-byte character set|DBCS]] (double-byte character set), this also meant that their width on screen in a [[duospaced font]] was proportional to their byte length. Some terminals and editing programs could not deal with double-byte characters starting at odd columns, only even ones (some could not even put double-byte and single-byte characters in the same line). So the DBCS sets generally included Roman characters and digits also, for use alongside the CJK characters in the same line.
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==In OpenType==
[[OpenType]] has the <code>fwid</code>, <code>halt</code>, <code>hwid</code>, and <code>vhal</code> feature tags to be used to reproduce fullwidth or halfwidth form of a character. [[CSS]] provides control over these fearuresfeatures using <code>font-variant-east-asian</code> and <code>font-feature-settings</code> properties.<ref>{{cite web |url=https://helpx.adobe.com/fonts/using/open-type-syntax.html |title=Syntax for OpenType features in CSS |publisher=[[Adobe Inc.|Adobe]] |access-date=2023-09-20}}</ref>
 
==See also==