Unicode has subscripted and superscripted versions of a number of characters including a full set of Arabic numerals. These characters allow any polynomial, chemical and certain other equations to be represented in plain text without using any form of markup like HTML or TeX.
The World Wide Web Consortium and the Unicode Consortium have made recommendations on the choice between using markup and using superscript and subscript characters:
When used in mathematical context (MathML) it is recommended to consistently use style markup for superscripts and subscripts.... However, when super and sub-scripts are to reflect semantic distinctions, it is easier to work with these meanings encoded in text rather than markup, for example, in phonetic or phonemic transcription.
The intended use when these characters were added to Unicode was to produce true superscripts and subscripts so that chemical and algebraic formulas could be written without markup. Thus "H₂O" (using a subscript 2 character) is supposed to be identical to "H2O" (with subscript markup).
In reality many fonts that include these characters ignore the Unicode definition, and instead design the digits for mathematical numerator and denominator glyphs, which are aligned with the cap line and the baseline, respectively. When used with the solidus, these glyphs are a common substitute for diagonal fractions, such as ³/₄ for the ¾ glyph. This change was made because using markup does not give a good graphic approximation of fractions (compare markup 3/4 with super/sub-script ³/₄). The change also makes the superscript letters useful for ordinal indicators, more closely matching the ª and º characters. However, it makes them incorrect for normal superscript and subscript, and so chemical and algebraic formulas are better rendered by using markup.
Unicode intended that diagonal fractions be rendered by a different mechanism: the fraction slash U+2044 is visually similar to the solidus, but when used with the ordinary digits (not the superscripts and subscripts), it instructs the layout system that a fraction such as ¾ is to be rendered using automatic glyph substitution.[a] User-end support was quite poor for a number of years, but browsers[b] and fonts increasingly support the intended Unicode behavior. A selection of supporting fonts is displayed in the table below. (These will not display properly if you do not have the fonts installed, or if your browser does not support this behavior.)
|Font||U+00BD ½ VULGAR FRACTION ONE HALF||U+0031 1 DIGIT ONE, |
U+2044 ⁄ FRACTION SLASH,
U+0032 2 DIGIT TWO
|Browser default font||½||1⁄2|
|Linux Libertine O||½||1⁄2|
Main article: Superscripts and Subscripts (Unicode block)
The most common superscript digits (1, 2, and 3) were in ISO-8859-1 and were therefore carried over into those positions in the Latin-1 range of Unicode. The rest were placed in a dedicated section of Unicode at U+2070 to U+209F. The two tables below show these characters. Each superscript or subscript character is preceded by a normal x to show the subscripting/superscripting. The table on the left contains the actual Unicode characters; the one on the right contains the equivalents using HTML markup for the subscript or superscript.
Unicode version 15.0 also includes subscript and superscript characters that are intended for semantic usage, in the following blocks:
Consolidated, the Unicode standard contains superscript and subscript versions of a subset of Latin, Greek and Cyrillic letters. Here they are arranged in alphabetical order for comparison (or for copy and paste convenience). Since these characters appear in different Unicode ranges, they may not appear to be the same size or position due to font substitution in the browser. Shaded cells mark small capitals that are not very distinct from minuscules, and Greek letters that are indistinguishable from Latin, and so would not be expected to be supported by Unicode.
Little punctuation is encoded. Parentheses and the exclamation mark are shown above. A question mark may be created with a superscript gelded question mark and a combining dot: ⟨ˀ̣⟩.
|Superscript small cap||||||||ᶦ||ᶫ||ᶰ||||ᶸ|||
* In some fonts, ᵅ and ᶹ can be used as superscript alpha and upsilon. ᵋ and ᶥ are also officially Latin letters, but display the same as Greek.
Many of the Cyrillic characters were added to Unicode 15, in the Cyrillic Extended-D block, and published in 2022. The D block was added to the free Gentium Plus and Andika fonts with version 6.2 in February 2023.
See also small caps in Unicode.
The Latin Extended-F block was created for superscript IPA letters. They were added to the free Gentium Plus and Andika fonts with version 6.2 in February 2023.
The Unicode characters for superscript (modifier) IPA and extIPA consonant letters are as follows. Characters for sounds with secondary articulation are set off in parentheses and placed below the base letters:
|ɡ ᶢ/g ᵍ
1D9C + 0327
|ʕ ˤ, ˁ
|Lateral approximant||l ˡ
The spacing diacritic for ejective consonants, U+2BC, works with superscript letters despite not being superscript itself: ⟨ᵖʼ ᵗʼ ᶜʼ ᵏˣʼ⟩. If a distinction needs to be made, the combining apostrophe U+315 may be used: ⟨ᵖ̕ ᵗ̕ ᶜ̕ ᵏˣ̕⟩. The spacing diacritic should be used for a baseline letter with a superscript release, such as [tˢʼ] or [kˣʼ], where the scope of the apostrophe includes the non-superscript letter, but the combining apostrophe U+315 might be used to indicate a weakly articulated ejective consonant like [ᵗ̕] or [ᵏ̕], where the whole consonant is written as a superscript, or together with U+2BC when separate apostrophes have scope over the base and modifier letters, as in ⟨pʼᵏˣ̕⟩.
Spacing diacritics, as in ⟨tʲ⟩, cannot be secondarily superscripted in plain text: ⟨ᵗʲ⟩. (In this instance, the old IPA letter for [tʲ], ⟨ƫ⟩, has a superscript variant in Unicode, U+1DB5 ⟨ᶵ⟩, as does the lateral, U+1DDA ⟨ᶪ⟩, but that is not generally the case.)
The Unicode characters for superscript (modifier) IPA vowel letters, plus an extended letter found in English dictionaries, are as follows. The two most recently retired alternative letters are also supported; they are set off in parentheses and placed below the standard IPA letters:
Note that the para-IPA letter for a central reduced vowel, ⟨ᵻ⟩, is supported, but its rounded equivalent, ⟨ᵿ⟩, is not.[note 7]
The precomposed Unicode rhotic vowel letters ⟨ɚ ɝ⟩ are not directly supported. The rhotic diacritic should be used instead: ⟨ᵊ˞ ᶟ˞⟩.
The two length marks are also supported:
Superscript wildcards (full caps) are partially supported: e.g. ᴺC (prenasalized consonant), N (prestopped nasal), P (fricative release), NᴾF (epenthetic plosive), CVNᵀ (tone-bearing syllable), Cᴸ (liquid or lateral release), Cᴿ (rhotic or resonant release), Vᴳ (off-glide/diphthong), Cⱽ (fleeting vowel). However, superscript S for sibilant release and superscript Ʞ for fleeting/epenthetic click are not supported as of Unicode 15. Other basic Latin superscript wildcards for tone and weak indeterminate sounds, as described in the article on the International Phonetic Alphabet, are mostly supported. (See table in previous section.)
In addition, a very few IPA letters beyond the basic Latin alphabet have combining superscript forms or are supported as subscripts:
Primarily for compatibility with earlier character sets, Unicode contains a number of characters that compose super- and subscripts with other symbols. In most fonts these render much better than attempts to construct these symbols from the above characters or by using markup.
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