Re: Ada 202x; 2022; and 2012 and Unicode package (UTF-nn encodings handling)

["Lawrence D’Oliveiro" <ldo@nz.invalid>]

On Tue, 2 Sep 2025 10:01:34 -0600, Alex // nytpu wrote:

> ... (UCS-4 has a number of additional differences from UTF-32
> regarding "valid encodings", namely that all valid Unicode
> codepoints (0x0--0x10FFFF inclusive) are allowed in UCS-4 but only
> Unicode scalar values (0x0--0xD7FF and 0xE000--0x10FFFF inclusive)
> are valid in UTF-32) ...

So what do those codes mean in UCS-4?

> ... and are missing some additional information: a key detail is
> that even with UTF-32 where each Unicode scalar value is held in one
> array element rather than being variable-width like UTF-8/UTF-16,
> you still can't treat them as arbitrary arrays like 7-bit ASCII
> because a grapheme can be made up of multiple Unicode scalar values.
> Even with ASCII characters there's the possibility of combining
> diacritics or such that would break if you split the string between
> them.

This is why you have “normalization”.
<https://www.unicode.org/faq/char_combmark.html>