Plain text custom fraction input

Marcel Schneider charupdate at
Thu Jul 23 04:45:14 CDT 2015

On 23 Jul 2015, at 01:06, Richard Wordingham  wrote:

> On Wed, 22 Jul 2015 12:21:32 +0200 (CEST)
> Marcel Schneider  wrote:
> > We never thought of common hieroglyphs otherwise as running LTR,
> > while on monuments the great liberty of the script allows to run in
> > amost all directions. IMO monumental transcription is always
> > difficult to deal with, whenever exact rendering is expected.
> > However, since Unicode's purpose is plain text encoding, we must
> > stick with what I consider as a convention in egyptology...
> Which means that Ancient Egyptian hieroglyphs are unencoded! Their
> default direction is right-to-left,

Sorry, I didn't know it, I must have forgotten. However, as Hans Aberg notes, they're facing writing direction, I remember that looking at the writing signs representing living creatures from the side, we can detect writing direction. I don't remember however that we'd to write ancient hieroglyphs from right to left. But one may do it without problems, except if...

> but that's only the start of the
> trouble. The encoded hieroglyphs aren't Bidi-mirrored,

That's really a pity. Hieroglyphs *must* be bidi-mirroring enabled to ensure the plain usefulness of the encoded characters. 

> so if I embed
> then in a right-to-left override, I should get retrograde characters.
> Now these aren't totally useless, but at present we seem to need a
> duplicate set of right-to-left hieroglyphs for unstacked text. There
> is work in progress to allow normal Egyptological hieroglyphic text.
> There seems to have been a change in the notion of what the Egyptian
> scripts are. Hieratic texts are normally printed in hieroglyphs for
> general study, so it had seemed that it would be legitimate to use a
> font that rendered a hieratic style rather than a hieroglyphic style.
> (Some 'hieroglyphs' only occurred in the hieratic style.) The
> hieratic style is strictly right-to-left, so rendering the text in a
> hieratic style would not be compliant with Unicode. However, it seems
> that the hieratic style is now a separate script, so any such
> rendering would now be doubly non-compliant. 
> > ...which brings us back to plain text fractions, which by an apparent
> > but tacit convention we can input as an *unlimited* string of
> > superscript digits, followed by U+2044, followed by an *unlimited*
> > string of subscript digits. What are you referring to when talking
> > about implementing the fraction slash?
> If you are happy with that style, I was wrong, I wasn't being clever
> enough.

It's a matter of practice! I wouldn't bother typing in super- and subscripts if I hadn't them on the keyboard layout :-)

> In a left to right context, the conversion of digits to the
> numerator and denominator forms can progress from right to left for the
> numerator by conditioning on the following character being a fraction
> slash or converted digit, and similarly from left to right for the
> denominator. I'm not sure what should happen in right to left
> contexts.

Sorry again, I wasn't really thinking about, even when yesterday I denied bidi-mirroring (I regretted soon), since the keyboard layout I'm programming is dedicated for use with Latin script. But I believe that the principles are portable to support other scripts, ideally *all* scripts.

> I've a feeling the numerator should come before the
> denominator, but the bidi algorithm doesn't swap them - it keeps the
> first number on the left. Note that subscript and superscript digits
> are only available for those of us who use the Western Arabic digits.

As I wrote to Khaled Hosny a few moments ago, I understand that fraction formatting is indispensible with Arabic (read: actual Arabic) digits.

> However, I believe there is a real problem for the 'nut' style, where
> the numerator and denominator are separated by a horizontal line - in
> Western Asia westwards. I'm having trouble finding examples of
> fractions using Indic scripts - apparently they originally stacked the
> numerator above the denominator, but I don't know what happens nowadays.

IMHO it would be hard to input fractions in nut style while using plain text or normal formatting, at the extent that we need the special Maths applications we know, from LibreOffice as far as I am concerned. But that isn't plain text. With the font-supported plain text fraction input as suggested, we can never get nut style, unfortunately. This is inimaginable *in plain text*.

> > If this input method is not encouraged, what's the use of U+215F
> It's for temporarily storing a character defined in some other coding
> standard.

It would be interesting to know more about this standard, and what was the use of this character in that standard, which seems to be hard to retrieve. What do you mean by "temporarily", given that Unicode code point allocations are stable? I'm very puzzled. I'd rather think that the inverse value as a "vulgar" fraction is so important that an input facility is provided, intended to be completed with subscript digits.

Best regards,

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