Suggestion for superscripts

William_J_G Overington wjgo_10009 at
Thu Jun 3 15:16:05 CDT 2021

Interestingly, many years ago Bernard Miller, in his Bytext proposal, 
suggested what he termed "arrow parentheses".

There were eight of them.

The glyphs were each either an opening or closing parenthesis character, 
with either one or two up arrows, or one or two down arrows upon the 

The single ones opened or closed a sequence of characters that were to 
be subscript or superscript, the double ones were for limits of definite 
integrals, summations and so on.

It seemed to me then, and does so now, to be a very good idea.

I am not an expert on Unicode and maybe there is some structural reason 
why this could not become implemented, even if people wanted it 

Yet I put this forward in the hope that the idea will be considered 
seriously please.

Here is a link to The Bytext Standard document.

Arrow parentheses are on pages 33 and 34.

Oh, and notwithstanding the comments about Bytext made in the mailing 
list thread at the time, please have a look at pages 37 and 38 and 
observe what was being suggested in 2002. Hmm.

William Overington

Thursday 3 June 2021

------ Original Message ------
From: "Don Peterson via Unicode" <unicode at>
To: unicode at
Sent: Thursday, 2021 Jun 3 At 19:29
Subject: Suggestion for superscripts

For about a decade I have been wanting to be able to print Unicode 
superscript characters in the output of some programs.  The most common 
use case for this is to print the exponents to physical units.  An 
example is kg·m/s², which is a bit easier on the eyes and brain than 

Unfortunately, the current version 13 character set doesn't have enough 
superscript characters to support common scientific usage.  From the 
ucd.nounihan.grouped XML file for version 13, these are the superscript 
and subscript characters I could find:

Superscripts: ⁰ ¹ ² ³ ⁴ ⁵ ⁶ ⁷ ⁸ ⁹ ⁺ ⁻ ⁼ ⁽ ⁾ ⁱ ⁿ
Subscripts:   ₀ ₁ ₂ ₃ ₄ ₅ ₆ ₇ ₈ ₉ ₊ ₋ ₌ ₍ ₎ ₐₑₕᵢⱼₖₗₘₙₒₚᵣₛₜᵤᵥₓᵦᵩ

Superscript characters are lacking for two fairly common use cases: 
floating point exponents and fractional exponents.  These would be 
possible with the addition to the superscripts of the two common radix 
characters '.' and ',' and a solidus character.  However, it seems to me 
that the Unicode design should aim at least at putting all printable 
7-bit ASCII characters and the upper and lower case Greek characters 
commonly used in technical work in both the subscript and superscript 
sets.  I've never commented on this before because I thought it was 
obvious and would be fixed in the next Unicode revision.  I remember 
looking at this pretty carefully around version 7 and being surprised by 
the lack.  Being a lazy retired person for the last 20 years meant I 
didn't do anything about it, which I now regret.  :^)

Because of this lack of superscript characters, one of my library 
functions is forced to produce syntactically-correct but ugly output 
such as m**0.75·Pa**-1.3·s⁻²·K⁻¹ for a units string input of "m(3/4) 
Pa(-1.3)/(s2*K)" (with syntax similar to the GNU units program).

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