Re: [Last-Call] New Version Notification for draft-crocker-inreply-react-07.txt

["Martin J. Dürst" <[e-mail]>]

Hello John, others,

Sorry this reply is late; I didn't get around to it yesterday.

On 03/03/2021 05:01, John C Klensin wrote:
> 
> 
> --On Tuesday, 02 March, 2021 15:48 +0900 "Martin J. Dürst"
> <[e-mail]> wrote:
> 
>> ...
>>> Note:
>>>       The "emoji" token looks simple. It isn't.
>>>   Implementors are  well-advised not to assume that emoji
>>> sequences are trivial to parse or  validate. Among other
>>> concerns, an implementation of the Unicode  Character
>>> Database is required. An emoji is more than a stand-in for a
>>> simple alternation of characters. Similarly, one emoji
>>> sequence is not  interchangeable with, or equivalent to,
>>> another one, and comparisons  require detailed understanding
>>> of the relevant Unicode mechanisms. Use  of an existing
>>> Unicode implementation will typically prove extremely
>>> helpful, as will an understanding of the error modes that may
>>> arise from  a chosen implementation.
>>
>> I think this is a valuable addition. I was following the
>> discussion for a long time, and wanted to point to the Unicode
>> implementations already existing out there and the high
>> probability that a mailer would use one of these, but Ned
>> finally pointed this out ahead of me.
> 
> Martin,
> 
> A question about the above.  When I first read the paragraph,
> "implementation of the Unicode  Character Database" struck me as
> strange, partially because I don't know what implementing a
> database means.  I would have thought the better wording would
> have been closer to "implementation of the rules of UTS#51 and
> the associated tables".  Do you agree?  If you (or others who
> are deeply steeped in Unicode) do not see a problem with the
> existing text, I'm happy to just let it go.

"implementation of the Unicode Character Database" indeed sounds 
somewhat strange. A first expansion could be "implementation of an API 
that gives access to the character properties defined in the Unicode 
Character Database", which would probably sound a bit more natural.

Such an implementation can be as a direct API (similar to the old C 
stdlib isupper and friends), as part of a regular expression engine, or 
in some other, more targeted form (e.g. some API tailored to IDNs or 
so). Actually implementing it involves downloading and parsing the data 
Unicode provides, selecting the data needed, and converting it to a form 
that can be used by the target environment (e.g. programming language,...).

Hope this helps. Please feel free to ask more if necessary, but 
preferably in another venue.

Regards,   Martin.