Date: Wed, 24 Jan 2024 13:22:08 -0500
Thanks for the clarification. That changes my mind; we should follow the
Unicode standard's recommendations and use U+03A9 (GREEK CAPITAL LETTER
OMEGA) for Ohm and U+00C5 (LATIN CAPITAL LETTER A WITH RING ABOVE) for
Angstrom.
On Wed, Jan 24, 2024 at 1:17 PM Robin Leroy <eggrobin_at_[hidden]> wrote:
> Le mer. 24 janv. 2024 à 17:50, Steve Downey <sdowney_at_[hidden]> a écrit :
>
>> I'd missed the discouraged part. Is that also the case for Angstrom, I
>> hope?
>>
>
> Le mer. 24 janv. 2024 à 18:52, Eddie Nolan via SG16 <sg16_at_[hidden]>
> a écrit :
>
>> With respect to unit symbols whose Unicode code points as units have
>> canonical equivalents as Greek letters, this was previously brought up in
>> the telecon on November 29, 2023 (minutes
>> <https://github.com/sg16-unicode/sg16-meetings/blob/340862b721050dbae5d35c96d1e62ecde7525206/README-2023.md#november-29th-2023>),
>> where I pointed out that the existing precedent in the standard is to use
>> the unit version, since iostream formatting of std::chrono::duration
>> uses U+00B5 (MICRO SIGN) rather than U+03BC (GREEK SMALL LETTER MU) for
>> microseconds. (See [time.duration.io]p(1,5)
>> <http://eel.is/c++draft/time.duration.io#1.5>).
>>
> Those cases are distinct; I suppose I should have quoted more context.
>
> *The Unicode Standard* reads, in Section 7.2 Greek, *sub* Greek Letters
> as Symbols
> <https://www.unicode.org/versions/Unicode15.1.0/ch07.pdf#G12477>,
>
>> For compatibility purposes, a few Greek letters are separately encoded as
>> symbols in other character blocks. Examples include U+00B5 µ MICRO SIGN in
>> the Latin-1 Supplement character block and U+2126 Ω OHM SIGN in the
>> Letterlike Symbols character block. The *ohm sign* is canonically
>> equivalent to the *capital omega*, and normalization would remove any
>> distinction. Its use is therefore discouraged in favor of *capital omega*.
>> The same equivalence does not exist between *micro sign* and *mu*, and
>> use of either character as a micro sign is common. For Greek text, only the
>> *mu* should be used.
>>
>
> ANGSTROM SIGN is, as Steve hopes, like OHM SIGN in that respect (see
> Section 22.2, *sub* Unit Symbols
> <https://www.unicode.org/versions/Unicode15.1.0/ch22.pdf#G20445>).
>
> Best regards,
>
> Robin Leroy
>
Unicode standard's recommendations and use U+03A9 (GREEK CAPITAL LETTER
OMEGA) for Ohm and U+00C5 (LATIN CAPITAL LETTER A WITH RING ABOVE) for
Angstrom.
On Wed, Jan 24, 2024 at 1:17 PM Robin Leroy <eggrobin_at_[hidden]> wrote:
> Le mer. 24 janv. 2024 à 17:50, Steve Downey <sdowney_at_[hidden]> a écrit :
>
>> I'd missed the discouraged part. Is that also the case for Angstrom, I
>> hope?
>>
>
> Le mer. 24 janv. 2024 à 18:52, Eddie Nolan via SG16 <sg16_at_[hidden]>
> a écrit :
>
>> With respect to unit symbols whose Unicode code points as units have
>> canonical equivalents as Greek letters, this was previously brought up in
>> the telecon on November 29, 2023 (minutes
>> <https://github.com/sg16-unicode/sg16-meetings/blob/340862b721050dbae5d35c96d1e62ecde7525206/README-2023.md#november-29th-2023>),
>> where I pointed out that the existing precedent in the standard is to use
>> the unit version, since iostream formatting of std::chrono::duration
>> uses U+00B5 (MICRO SIGN) rather than U+03BC (GREEK SMALL LETTER MU) for
>> microseconds. (See [time.duration.io]p(1,5)
>> <http://eel.is/c++draft/time.duration.io#1.5>).
>>
> Those cases are distinct; I suppose I should have quoted more context.
>
> *The Unicode Standard* reads, in Section 7.2 Greek, *sub* Greek Letters
> as Symbols
> <https://www.unicode.org/versions/Unicode15.1.0/ch07.pdf#G12477>,
>
>> For compatibility purposes, a few Greek letters are separately encoded as
>> symbols in other character blocks. Examples include U+00B5 µ MICRO SIGN in
>> the Latin-1 Supplement character block and U+2126 Ω OHM SIGN in the
>> Letterlike Symbols character block. The *ohm sign* is canonically
>> equivalent to the *capital omega*, and normalization would remove any
>> distinction. Its use is therefore discouraged in favor of *capital omega*.
>> The same equivalence does not exist between *micro sign* and *mu*, and
>> use of either character as a micro sign is common. For Greek text, only the
>> *mu* should be used.
>>
>
> ANGSTROM SIGN is, as Steve hopes, like OHM SIGN in that respect (see
> Section 22.2, *sub* Unit Symbols
> <https://www.unicode.org/versions/Unicode15.1.0/ch22.pdf#G20445>).
>
> Best regards,
>
> Robin Leroy
>
Received on 2024-01-24 18:22:20