Re: [icu-support] ISO15924 numeric codes

[Markus S. <mar...@gm...>]

On Tue, Nov 11, 2014 at 5:45 AM, Benson Margulies <bim...@gm...>
wrote:

> UScript claims that it is defining constants for ISO15924.


More precisely: "Constants for ISO 15924 script codes." And the discussion
in the API docs is about the 4-letter script codes.

But the
> numbers in there bear no obvious relationship to
>
>
> http://www.unicode.org/iso15924/iso15924-num.html
>
> For example, Arab = 160 in the ISO standard, but 2 in Uscript.
>

As you can see, the UScriptCode
<http://bugs.icu-project.org/trac/browser/icu/trunk/source/common/unicode/uscript.h>
constants are in the order of their assignment, and alphabetical within
added-in-same-ICU-version chunks.

You could submit an ICU ticket for clarifying in the API docs that the
numeric values of the enum constants have no meaning. (They are stable but
meaningless.)

UTR#24 did not seem to illuminate me.
>

UAX #24 does not discuss numeric script codes at all, and the UCD does not
define numeric script property value aliases
<http://www.unicode.org/Public/UCD/latest/ucd/PropertyValueAliases.txt>.

If you would like some text to be added to UAX #24 about numeric script
codes, then please use the Unicode reporting form.

I don't actually know why ISO 15924 defines numeric codes; the alpha4 codes
are widely used.
What is your use case for the numeric codes?

Best regards,
markus