Halfwidth and Fullwidth Forms
Encyclopedia
In CJK
computing, graphic character
s are traditionally classed into fullwidth (in Taiwan
and Hong Kong
: 全形; in Japan and Korea: 全角) and halfwidth (in Taiwan
and Hong Kong
: 半形; in Japan and Korea: 半角) characters. With fixed-width fonts, a halfwidth character occupies half the width of a fullwidth character, hence the name.
In the days of computer terminal
s and text mode
computing, characters were normally laid out in a grid, often 80 columns by 24 or 25 lines. Each character was displayed as a small dot matrix
, often about 8 pixel
s wide, and an SBCS
(single byte character set) was generally used to encode characters of western languages.
For a number of practical and aesthetic reasons, Han characters would need to be twice as wide as these fixed-width SBCS characters. These "fullwidth characters" were typically encoded in a DBCS
(double byte character set), although less common systems used other variable-width character sets that used more bytes per character.
Halfwidth and Fullwidth Forms is also the name of a Unicode block
U+FF00–FFEF.
, if a certain grapheme can be represented as either a fullwidth character or a halfwidth character, it is said to have both a fullwidth form and a halfwidth form.
Halfwidth and Fullwidth Forms is the name of Unicode block
U+FF00–FFEF, the last of the Basic Multilingual Plane excepting the short Specials
block at U+FFF0–FFFF.
Range U+FF01–FF5E reproduces the characters of ASCII
21 to 7E as fullwidth forms, that is, a fixed width form used in CJK
computing. This is useful for typesetting Latin characters in a CJK
environment. U+FF00 does not correspond to a fullwith ASCII 20 (space character), since that role is already fulfilled by U+3000 "ideographic space."
Range U+FF65–FFDC encodes halfwidth forms of Katakana
and Hangul
characters – see half-width kana
. Range U+FFE0–FFEE includes fullwidth and halfwidth symbols.
CJK
CJK is a collective term for Chinese, Japanese, and Korean, which is used in the field of software and communications internationalization.The term CJKV means CJK plus Vietnamese, which constitute the main East Asian languages.- Characteristics :...
computing, graphic character
Graphic character
In ISO/IEC 646 and related standards including ISO 8859 and Unicode, a graphic character is any character intended to be written, printed, or otherwise displayed in a form that can be read by humans...
s are traditionally classed into fullwidth (in Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
and Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
: 全形; in Japan and Korea: 全角) and halfwidth (in Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
and Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
: 半形; in Japan and Korea: 半角) characters. With fixed-width fonts, a halfwidth character occupies half the width of a fullwidth character, hence the name.
In the days of computer terminal
Computer terminal
A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system...
s and text mode
Text mode
Text mode is a kind of computer display mode in which the content of the screen is internally represented in terms of characters rather than individual pixels. Typically, the screen consists of a uniform rectangular grid of character cells, each of which contains one of the characters of a...
computing, characters were normally laid out in a grid, often 80 columns by 24 or 25 lines. Each character was displayed as a small dot matrix
Dot matrix
A dot matrix is a 2-dimensional array of LED used to represent characters, symbols and images.Typically the dot matrix is used in older computer printers and many digital display devices. In printers, the dots are usually the darkened areas of the paper...
, often about 8 pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
s wide, and an SBCS
SBCS
SBCS, or Single Byte Character Set, is used to refer to character sets which use exactly one byte for each graphic character. SBCS can accommodate a maximum of 256 symbols, and were originally essentially built for the English language because English does not have many symbols or accented letters...
(single byte character set) was generally used to encode characters of western languages.
For a number of practical and aesthetic reasons, Han characters would need to be twice as wide as these fixed-width SBCS characters. These "fullwidth characters" were typically encoded in a DBCS
DBCS
A double-byte character set is a character set that represents each character with 2 bytes. The DBCS supports national languages that contain a large number of unique characters or symbols...
(double byte character set), although less common systems used other variable-width character sets that used more bytes per character.
Halfwidth and Fullwidth Forms is also the name of a Unicode block
Unicode block
In Unicode, a block is defined as one contiguous range of code points. Blocks are named uniquely and have no overlap. They may be defined with the starting and ending code points. The block explicitly can include code points that are unassigned and non-characters. Code points not belonging to any...
U+FF00–FFEF.
In Unicode
In UnicodeUnicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
, if a certain grapheme can be represented as either a fullwidth character or a halfwidth character, it is said to have both a fullwidth form and a halfwidth form.
Halfwidth and Fullwidth Forms is the name of Unicode block
Unicode block
In Unicode, a block is defined as one contiguous range of code points. Blocks are named uniquely and have no overlap. They may be defined with the starting and ending code points. The block explicitly can include code points that are unassigned and non-characters. Code points not belonging to any...
U+FF00–FFEF, the last of the Basic Multilingual Plane excepting the short Specials
Unicode Specials
Specials is the name of a short Unicode block allocated at the very end of the Basic Multilingual Plane, at U+FFF0–FFFF. Of these 16 codepoints, 5 are assigned as of Unicode 6.0:, marks start of annotated text, marks start of annotating text, marks end of annotating text, placeholder in the...
block at U+FFF0–FFFF.
Range U+FF01–FF5E reproduces the characters of ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
21 to 7E as fullwidth forms, that is, a fixed width form used in CJK
CJK
CJK is a collective term for Chinese, Japanese, and Korean, which is used in the field of software and communications internationalization.The term CJKV means CJK plus Vietnamese, which constitute the main East Asian languages.- Characteristics :...
computing. This is useful for typesetting Latin characters in a CJK
CJK
CJK is a collective term for Chinese, Japanese, and Korean, which is used in the field of software and communications internationalization.The term CJKV means CJK plus Vietnamese, which constitute the main East Asian languages.- Characteristics :...
environment. U+FF00 does not correspond to a fullwith ASCII 20 (space character), since that role is already fulfilled by U+3000 "ideographic space."
Range U+FF65–FFDC encodes halfwidth forms of Katakana
Katakana
is a Japanese syllabary, one component of the Japanese writing system along with hiragana, kanji, and in some cases the Latin alphabet . The word katakana means "fragmentary kana", as the katakana scripts are derived from components of more complex kanji. Each kana represents one mora...
and Hangul
Hangul
Hangul,Pronounced or ; Korean: 한글 Hangeul/Han'gŭl or 조선글 Chosŏn'gŭl/Joseongeul the Korean alphabet, is the native alphabet of the Korean language. It is a separate script from Hanja, the logographic Chinese characters which are also sometimes used to write Korean...
characters – see half-width kana
Half-width kana
are katakana characters displayed at half their normal width , instead of the usual square aspect ratio. For example, the usual form of the katakana ka is カ while the half-width form is ｶ...
. Range U+FFE0–FFEE includes fullwidth and halfwidth symbols.
See also
- CJKCJKCJK is a collective term for Chinese, Japanese, and Korean, which is used in the field of software and communications internationalization.The term CJKV means CJK plus Vietnamese, which constitute the main East Asian languages.- Characteristics :...
- Han unificationHan unificationHan unification is an effort by the authors of Unicode and the Universal Character Set to map multiple character sets of the so-called CJK languages into a single set of unified characters. Han characters are a common feature of written Chinese , Japanese , Korean , and—at least historically—other...
- Half-width kanaHalf-width kanaare katakana characters displayed at half their normal width , instead of the usual square aspect ratio. For example, the usual form of the katakana ka is カ while the half-width form is ｶ...
- Monospace (disambiguation)
- East Asian punctuation (disambiguation)
External links
- http://www.alanwood.net/unicode/halfwidth_and_fullwidth_forms.html
- http://everything2.com/index.pl?node=Halfwidth%20and%20Fullwidth%20Forms
- Fullwidth character converter http://www.businessinfo.co.uk/labs/hackvertor/hackvertor.php?input=PEB1bmlfaHdmd19jaGFycz4iPjxzY3JpcHQ%2BYWxlcnQoMSk8L3NjcmlwdD48QC91bmlfaHdmd19jaGFycz4%3D