Plain text custom fraction input (Child thread of: Input methods at the age of Unicode)

Marcel Schneider charupdate at
Mon Jul 20 02:39:30 CDT 2015


I've got a concern about entering customized (vulgar) fractions in plain text, using a sequence of superscript and subscript digits separated by U+2044 FRACTION SLASH. I submitted it in PRI#297. 
As I need to clear up this point for future keyboard layout usage recommendations, I would like to submit this to the attention of the Unicode Mailing List for advice and discussion.

A demo file opening in a word processor, typeset in Arial Unicode MS
typeface, is available at
To view it in PDF, there is another file at

The following is based on

Date/Time: Mon Apr 13 10:07:49 CDT 2015
There is some additional information about U+2044 FRACTION SLASH I would
suggest adding at the “Fraction Slash” paragraphs in the “Other Punctuation”
subsection of §6.2, page 273 of the Standard, as well as in the Code Charts’
Fractions subheader before U+2150.

U+2044 FRACTION SLASH working together with superscripts and subscripts is so
obvious no discussion is needed.
[Note: This proved to be wrong. I'm sorry not to have e-mailed this to the List.]
On the other hand, as fraction formatting
needs at least desktop publishing software, it is usually not a part of office
automation. It seems therefore useful to show the plain text entering method
for (so-called vulgar) fractions.

The "Number Forms" block’s "Fractions" subhead may therefore be followed by a
NOTICE_LINE like this one: ‘@+’ [TAB] [TAB] ‘Fractions may be composed in
plain text on a [superscripts] 2044 [subscripts] pattern.’

On the other hand, the Fraction Slash notice in the Standard might contain the informations 
below (including those already provided in the Standard).
Fraction Slash. U+2044 FRACTION SLASH is used between digits to form numeric
fractions. It is kerning for use with superscripts and subscripts to compose
plain text fractions such as ²⁄₃ and ³⁄₉.The pattern of a plain text fraction
built using the fraction slash is defined as follows: any sequence of one or
more superscript digits (U+00B9, U+00B2, U+00B3, U+2074 - U+2079, U+2070),
followed by the fraction slash, followed by any sequence of one or more
subscript digits (U+2080 - U+2089).

U+2044 FRACTION SLASH may also act as a formatting command for use with
decimal digits, and it may be used instead of U+002F SOLIDUS prior to applying
fraction formatting. The standard form of a fraction designed for formatting
is defined as follows: any sequence of one or more decimal digits (General
Category = Nd), followed by the fraction slash, followed by any sequence of
one or more decimal digits. If the fraction is to be separated from a previous
number, then a space can be used, choosing the appropriate width (normal,
thin, zero width, and so on). For example, 1 + thin space + 3 + fraction slash
+ 4 can be displayed as 1¾.

Whether they are plain text or formatted, fractions should be displayed as a
unit, such as ¾ or {unavailable glyph}. The precise choice of display can
depend on additional formatting information. If the displaying software is
incapable of mapping the fraction to a unit, then it can also be displayed as
a simple linear sequence as a fallback (for example, 3/4). For fallback
display, U+002F SOLIDUS is preferred, because the fraction slash kerns.
Date/Time: Wed Apr 22 11:26:44 CDT 2015
Opt Subject: PRI #297 Fraction slash


Additionally to a previous feedback, I would suggest adding the hint about how
to compose arbitrary fractions in plain text, in another place as well. This
could be the entry of the fraction slash U+2044 and, more precisely, the end
of the existing COMMENT_LINE, after a comma:

= solidus (in typography)
* for composing arbitrary fractions, in plain text with superscripts and subscripts.

Thank you for feedback.
Best regards,

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