Transform rule syntax clarifications

[Martin J. Dürst via CLDR-Users]

Hello Mark,

On 2019/11/18 19:41, Mark Davis ☕️ wrote:
> I was about to point people to that, and request people to add additional
> comments on clarifications of the syntax, but I couldn't find your ticket
> at https://unicode-org.atlassian.net/issues/?filter=10033. Did you file it
> for CLDR?

I filed it at https://www.unicode.org/reporting.html, because I thought 
that that was where to file for UTS #35. Feel free to transfer it from 
there to wherever you think it should go.

Regards,   Martin.

> Mark
> 
> 
> On Mon, Nov 18, 2019 at 9:03 AM Martin J. Dürst <duerst at it.aoyama.ac.jp>
> wrote:
> 
>> On 2019/11/18 17:22, Mark Davis ☕️ wrote:
>>> It should use A∖B when taking about the math operation. Could you file a
>>> ticket?
>>
>> Done.   Regards,   Martin.
>>
>>> {phone}
>>>
>>> On Mon, Nov 18, 2019, 04:42 Martin J. Dürst via CLDR-Users <
>>> cldr-users at unicode.org> wrote:
>>>
>>>> On 2019/11/17 11:37, Richard Wordingham via CLDR-Users wrote:
>>>>> On Sat, 16 Nov 2019 13:18:00 -0800
>>>>> Cameron Dutro via CLDR-Users <cldr-users at unicode.org> wrote:
>>>>>
>>>>>> The other bits of syntax you've mentioned are from the Unicode Set
>>>>>> specification, which you can find in UTS #35
>>>>>> <https://unicode.org/reports/tr35/#Unicode_Sets>. Unicode Sets are
>>>>>> like regex character classes, but as you've noticed, there are a
>>>>>> couple of special operations they support that regexes don't.
>>>>>> Specifically, the "-" operator is the symmetric difference
>>>>>> <https://en.wikipedia.org/wiki/Symmetric_difference> between the two
>>>>>> operands (UTS 35 says "asymmetric difference," but I don't think
>>>>>> that's a thing - I can't find any definition of it online).
>>>>>
>>>>> It very much is a thing!
>>>>
>>>> Well, yes, except that it's usually just called "set difference" without
>>>> an explicit adjective. (I'd strongly suggest that UTS 35 put the word
>>>> 'asymmetric' in parentheses.) Also, one wouldn't use the symbol '-' for
>>>> symmetric difference.
>>>>
>>>> Regards,   Martin.
>>>>
>>>>> In this particular case,
>>>>>
>>>>> $accent_minus = [[$accent]-[$iotasub$macron]];
>>>>>
>>>>> is probably the same as the symmetric difference, because from
>>>>> the names i think everything in the second set is in the first set, but
>>>>> this doesn't always apply.  [abcd] - [abef] is [cd], not the symmetric
>>>>> difference [cdef].
>>>>>
>>>>> Richard.
>>>
>>
>