Zero-width space
The zero-width space (), abbreviated ZWSP, is a non-printing character used in computerized typesetting to indicate where the word boundaries are, without actually displaying a visible space in the rendered text. This enables text-processing systems for scripts that do not use explicit spacing to recognize where word boundaries are for the purpose of handling line breaks appropriately.
The zero-width space is Unicode character U+200B, and is located in the Unicode General Punctuation block. In HTML, it can be represented by the character entity reference ​.
Purpose
[edit]The zero-width space marks a potential line break without hyphenation. Its semantics and HTML implementation are similar to the soft hyphen, but soft hyphens display a hyphen character at the point where the line is broken.
The zero-width space can be used to mark word breaks in languages without visible space between words, such as Thai, Myanmar, Khmer, and Japanese.[1]
In justified text, the rendering engine may add inter-character spacing, also known as letter spacing, between letters separated by a zero-width space, unlike around fixed-width spaces.[1]
Example
[edit]To show the effect of the zero-width space in text, the following words have been separated with zero-width spaces:
LoremIpsumDolorSitAmetConsecteturAdipiscingElitSedDoEiusmodTemporIncididuntUtLaboreEtDoloreMagnaAliquaUtEnimAdMinimVeniamQuisNostrudExercitationUllamcoLaborisNisiUtAliquipExEaCommodoConsequatDuisAuteIrureDolorInReprehenderitInVoluptateVelitEsseCillumDoloreEuFugiatNullaPariaturExcepteurSintOccaecatCupidatatNonProidentSuntInCulpaQuiOfficiaDeseruntMollitAnimIdEstLaborum
By contrast, the following words have not been separated:
LoremIpsumDolorSitAmetConsecteturAdipiscingElitSedDoEiusmodTemporIncididuntUtLaboreEtDoloreMagnaAliquaUtEnimAdMinimVeniamQuisNostrudExercitationUllamcoLaborisNisiUtAliquipExEaCommodoConsequatDuisAuteIrureDolorInReprehenderitInVoluptateVelitEsseCillumDoloreEuFugiatNullaPariaturExcepteurSintOccaecatCupidatatNonProidentSuntInCulpaQuiOfficiaDeseruntMollitAnimIdEstLaborum
The first text is broken into lines but only at word boundaries, and resizing the browser window will re-break the text accordingly, while the second text is not broken at all.
Usage
[edit]HTML
[edit]In HTML pages, the HTML element <wbr> functions as a zero-width space. In Internet Explorer 6, the zero-width space was not supported in some fonts.[2]
Prohibition in domain names
[edit]ICANN rules prohibit domain names from containing non-displayed characters, including the zero-width space, and most browsers prohibit their use within domain names because they can be used to create a homograph attack, where a malicious URL is visually indistinguishable from a legitimate one.[3][4]
Encoding
[edit]The zero-width space character is encoded in Unicode as U+200B ZERO WIDTH SPACE.[5]
In HTML, it can be referenced as ​, ​ or ​. Additionally, the character entities ​, ​, ​, and ​ all also refer to the zero-width space, contrary to what their names suggest.[6]
The TeX representation is \hskip0pt; the LaTeX representation is \hspace{0pt};[7] and the groff representation is \:.[8]
See also
[edit]- Hair space
- Whitespace character – including a table comparing various space-like characters
- Word divider
- Word wrapping
- Word joiner (U+2060: ), as well as zero-width no-break space (U+FEFF: )
- Zero-width joiner (U+200D: )
- Zero-width non-joiner (U+200C: )
References
[edit]Citations
[edit]- ^ a b "23.2 Layout Controls". The Unicode® Standard Version 15.0 – Core Specification (PDF). The Unicode Consortium. September 2022. p. 918. ISBN 978-1-936213-32-0.
- ^ Dunae, Alex. "Better Web Typography with Spaces and Hyphens". dunae.ca. Archived from the original on December 14, 2010. Retrieved December 3, 2009.
- ^ "Network.IDN.blacklist_chars". mozillaZine. Retrieved 2018-02-07.
- ^ "Unicode Character 'Zero Width Space'". FileFormat.Info. Retrieved 2018-02-07.
- ^ "General Punctuation – Unicode" (PDF). Retrieved 2013-07-20.
- ^ Entities/ZeroWidthSpace in MathML Version 2.0
- ^ "The LaTeX Companion. Chapter 3: Basic Formatting Tools" (PDF). Retrieved 2019-07-16.
- ^ "groff(7) – Linux manual page". Retrieved 2014-02-08.
Sources
[edit]- Mair, Victor H.; Liu, Yongquan (1991), Characters and computers, IOS Press
