Variation Sequences (and L2-11/059)

[Janusz S. Bień via Unicode]

On Mon, Jul 16 2018 at 19:00 +0100, wjgo_10009 at btinternet.com writes:
> Hi
>
>> I ask the question because there are now several historical corpora
>> of Polish under development, which use at present a kind of fall-back
>> or some other ad hoc solutions for "nonce glyphs", as they are called
>> in the FAQ.
>
> I wonder if you could say please what are the "kind of fall-back or
> some other ad hoc solutions" please.

I would prefer not to go into details. I think some of those "solutions"
are simply wrong but the list is not the right place to criticize them.

> The reason I ask is because I have thought of a possible solution to
>the problem that has graceful fall-back and uses only plane 0
>characters, no Private Use Area characters at all: I am wondering
>whether my suggestion will be of use or if it is just another method
>that could just be added to a collection of "kind of fall-back or some
>other ad hoc solutions".
> My suggestion is to use for each desired glyph a sequence consisting
> of three characters, and then have an OpenType font decode them so
> that the glyph can be displayed.

This is a prohibitive requirement, because for years there is the lack
of font creators interested in old Polish.

> Each such sequence being of the form.
>
> Base character ZERO WIDTH JOINER then a circled digit character or a circled number character.
>
> http://www.unicode.org/charts/PDF/U2460.pdf
>
> Thus there being up to twenty specific glyphs for each base character.
>
> The list of glyphs could be gradually extended as needed and if an
> attempt to display a newly added glyph is made using a font
> implemented from an earlier list then there would be graceful
> fall-back to the base character followed by a circled digit.
>
> It would be helpful for entering text into documents if the ZERO WIDTH
> JOINER character has a visible glyph within the font. Then entering
> text with OpenType glyph substitution turned off could be easier to
> carry out.

I perceive your proposal as "visible variant selectors for private
variation sequences", as a text encoded this way can be easily converted
into a text using real variant selectors.

I think it might be a reasonable temporary solution, but not the
ultimate one.

> I am wondering quite how acceptable such a solution would be for
> standardization: the list of ways that something can be encoded using
> a ZWJ (ZERO WIDTH JOINER) character seems to have recently been de
> facto extended for use with generating emoji sequences - not with
> circled digits but use of ZWJ to change meaning which is a far bigger
> extension than needed for this suggestion as meaning would often be
> unaltered when using this suggestion.

I would expect arguments that is has no obvious advantage over
variations sequences.

Best regards

Janusz

-- 
             ,   
Janusz S. Bien
emeryt (emeritus)
https://sites.google.com/view/jsbien