The ISO Latin 1 character repertoire – a description with usage notes, section 3 The characters grouped by type, with annotations:

Digits (0 - 9), superscript digits (  ), and vulgar fractions (  )

The "normal" digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 are often called Arabic digits (especially to distinguish them from Roman numerals like XIV). In fact, Western Europeans adopted them from the Arabs, who had adopted them from scripts used in India. In these processes, the shapes of digits changed, however. The digits used in Arabic writing have shapes which differ from those of these "Arabic" digits, and they are classified as separate characters in Unicode: they are "Arabic-Indic digits" in block Arabic. There are also several other sets of digits in Unicode, for use in different scripts.

In Unicode, there are distinct characters for digits used as superscripts or subscripts. Only the superscripts corresponding to 1, 2 and 3, that is and and , belong to ISO Latin 1; the others are in block Superscripts and Subscripts in Unicode. Notice that ISO Latin 1 repertoire contains two characters which may look like superscript 0: the degree sign () and the masculine ordinal indicator ().

When using the ISO Latin character repertoire only, it is probably best to use superscript or or only if all superscripts used in a document can be expressed that way. Otherwise, i.e. when you need to use some other method for presenting other superscripts (such as the SUP element when authoring in HTML), it is probably best to use that method throughout, for uniformity.

The so-called vulgar fractions are characters denoting fractional numbers as single characters. In ISO Latin 1, there are such characters for the fractions 1/4, 1/2, 3/4 (namely   ). This reflects the character repertoire on many typewriters. Depending on the font, the bar (which corresponds to fraction slash) can be horizontal or slanted.

Analogously with the situation with superscript digits, when using the ISO Latin 1 character repertoire only, it is probably best to use vulgar fractions only if all fractions used in a document can be expressed that way. Otherwise, i.e. when you need to use some other method for presenting other fractions it is probably best to use that method throughout, for uniformity. You could use simply expressions like 2/3 and 1/4. (In the HTML language, you might use the SUP markup for the nominator and the SUB markup for the denominator, thereby suggesting a presentation which somewhat resembles vulgar fractions in appearance. However, such markup may cause uneven line spacing. See also section Fractions in Math in HTML.)

A practical problem with the vulgar fraction characters is that their appearance is often hard to read, especially on computer screens.

In Unicode, both the superscripts and the vulgar fractions are compatibility characters, so that e.g. the compatibility decomposition of is 3/4 presented in "fraction style".


Originally created 2000-03-31. Structurally changed 2018-10-16. Minor modifications 2018-12-15.
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