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Halfwidth and Fullwidth Forms (Unicode block)

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Halfwidth and Fullwidth Forms
RangeU+FF00..U+FFEF
(240 code points)
PlaneBMP
ScriptsHangul (52 char.)
Katakana (55 char.)
Latin (52 char.)
Common (66 char.)
Symbol setsVariant width characters
Assigned225 code points
Unused15 reserved code points
Unicode version history
1.0.0 (1991)216 (+216)
1.1 (1993)223 (+7)
3.2 (2002)225 (+2)
Unicode documentation
Code chart ∣ Web page
Note: [1][2][3]

Halfwidth and Fullwidth Forms is the name of a Unicode block U+FF00–FFEF, provided so that older encodings containing both halfwidth and fullwidth characters can have lossless translation to/from Unicode. It is the second-to-last block of the Basic Multilingual Plane, followed only by the short Specials block at U+FFF0–FFFF. Its block name in Unicode 1.0 was Halfwidth and Fullwidth Variants.[4]

Range U+FF01–FF5E reproduces the characters of ASCII 21 to 7E as fullwidth forms. U+FF00 does not correspond to a fullwidth ASCII 20 (space character), since that role is already fulfilled by U+3000 "ideographic space".

Range U+FF61–FF9F encodes halfwidth forms of katakana and related punctuation in a transposition of A1 to DF in the JIS X 0201 encoding – see half-width kana.

The range U+FFA0–FFDC encodes halfwidth forms of compatibility jamo characters for Hangul, in a transposition of their 1974 standard layout. It is used in the mapping of some IBM encodings for Korean, such as IBM code page 933, which allows the use of the Shift Out and Shift In characters to shift to a double-byte character set.[5] Since the double-byte character set could contain compatibility jamo, halfwidth variants are needed to provide round-trip compatibility.[6][7]

Range U+FFE0–FFEE includes fullwidth and halfwidth symbols.

Block

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Halfwidth and Fullwidth Forms[1][2]
Official Unicode Consortium code chart (PDF)
  0 1 2 3 4 5 6 7 8 9 A B C D E F
U+FF0x
U+FF1x
U+FF2x
U+FF3x _
U+FF4x
U+FF5x
U+FF6x
U+FF7x ソ
U+FF8x
U+FF9x
U+FFAx  HW 
HF
U+FFBx
U+FFCx
U+FFDx
U+FFEx
Notes
1.^ As of Unicode version 16.0
2.^ Grey areas indicate non-assigned code points

The block has variation sequences defined for East Asian punctuation positional variants.[8][9] They use U+FE00 VARIATION SELECTOR-1 (VS01) and U+FE01 VARIATION SELECTOR-2 (VS02):

Variation sequences for punctuation alignment
U+ FF01 FF0C FF0E FF1A FF1B FF1F Description
base code point
base + VS01 !︀ ,︀ .︀ :︀ ;︀ ?︀ corner-justified form
base + VS02 !︁ ,︁ .︁ :︁ ;︁ ?︁ centered form

An additional variant is defined for a fullwidth zero with a short diagonal stroke: U+FF10 FULLWIDTH DIGIT ZERO, U+FE00 VS1 (0︀).[10][9]

History

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The following Unicode-related documents record the purpose and process of defining specific characters in the Halfwidth and Fullwidth Forms block:

See also

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References

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  1. ^ "Unicode 1.0.1 Addendum" (PDF). The Unicode Standard. 1992-11-03. Retrieved 2016-07-09.
  2. ^ "Unicode character database". The Unicode Standard. Retrieved 2023-07-26.
  3. ^ "Enumerated Versions of The Unicode Standard". The Unicode Standard. Retrieved 2023-07-26.
  4. ^ "3.8: Block-by-Block Charts" (PDF). The Unicode Standard. version 1.0. Unicode Consortium.
  5. ^ "ICU Demonstration - Converter Explorer". demo.icu-project.org. Retrieved 7 May 2018.
  6. ^ "Halfwidth and Fullwidth blame".
  7. ^ "Conversion Data - Old location of the ICU User Guide".
  8. ^ Lunde, Ken (2018-01-21). "L2/17-436: Proposal to add standardized variation sequences for fullwidth East Asian punctuation" (PDF).
  9. ^ a b "Unicode Character Database: Standardized Variation Sequences". The Unicode Consortium.
  10. ^ Beeton, Barbara; Freytag, Asmus; Iancu, Laurențiu; Sargent, Murray (2015-10-30). "L2/15-268: Proposal to Represent the Slashed Zero Variant of Empty Set" (PDF).