On 8/7/2019 5:08 PM, Andrew Glass wrote:
Shaping domain names is a new requirement. It would be good to
understand the specific cases that are falling in the gap here.
Domain names are simply strings, but the protocol enforces normalization
to NFC. In some situations, it might be possible for a browser, for
example, to have access to the user-provided string, but I can see any
number of situations where the actual string (as stored in the DNS)
would need to be displayed.
For the scenario, it does not matter whether it's NFC or NFD, what
matters is that some particular un-normalized state would be lost; and
therefore it would be bad if the result is that the string can no longer
be rendered correctly.
In particular, as the strings in question would be identifiers, where
accurate recognition is prime.
A./
*From:*Unicode <unicode-boun...@unicode.org> *On Behalf Of *Asmus
Freytag via Unicode
*Sent:* 07 August 2019 14:19
*To:* unicode@unicode.org
*Subject:* Re: What is the time frame for USE shapers to provide
support for CV+C ?
What about text that must exist normalized for other purposes?
Domain names must be normalized to NFC, for example. Will such strings
display correctly if passed to USE?
A./
On 8/7/2019 1:39 PM, Andrew Glass via Unicode wrote:
That's correct, the Microsoft implementation of USE spec does not normalize
as part of the shaping process.
Why? Because the ccc system for non-Latin scripts is not a good mechanism
for handling complex requirements for these writing systems and the effects of
ccc-based normalization can disrupt authors intent. Unfortunately, because we
cannot fix ccc values, shaping engines at Microsoft have ignored them.
Therefore, recommendation for passing text to USE is to not normalize.
By the way, at the current time, I do not have a final consensus from Tai
Tham experts and community on the changes required to support Tai Tham in USE.
Therefore, I've not been able to make the changes proposed in this thread.
Cheers,
Andrew
-----Original Message-----
From: Richard Wordingham<richard.wording...@ntlworld.com> <mailto:richard.wording...@ntlworld.com>
Sent: 07 August 2019 13:29
To: Richard Wordingham via Unicode<unicode@unicode.org>
<mailto:unicode@unicode.org>
Cc: Andrew Glass<andrew.gl...@microsoft.com>
<mailto:andrew.gl...@microsoft.com>
Subject: Re: What is the time frame for USE shapers to provide support for
CV+C ?
On Tue, 14 May 2019 03:08:04 +0100
Richard Wordingham via Unicode<unicode@unicode.org>
<mailto:unicode@unicode.org> wrote:
On Tue, 14 May 2019 00:58:07 +0000
Andrew Glass via Unicode<unicode@unicode.org>
<mailto:unicode@unicode.org> wrote:
Here is the essence of the initial changes needed to support CV+C.
Open to feedback.
* Create new SAKOT class
SAKOT (Sk) based on UISC = Invisible_Stacker
* Reduced HALANT class
Now only HALANT (H) based on UISC = Virama
* Updated Standard cluster mode
[< R | CS >] < B | GB > [VS] (CMAbv)* (CMBlw)* (< < H | Sk > B | SUB
[VS] (CMAbv)* (CMBlw)*)* [MPre] [MAbv] [MBlw] [MPst] (VPre)*
(VAbv)* (VBlw)* (VPst)* (VMPre)* (VMAbv)* (VMBlw)* (VMPst)* (Sk
B)* (FAbv)* (FBlw)* (FPst)* [FM]
This next question does not, I believe, affect HarfBuzz. Will NFC
code render as well as unnormalised code? In the first example above,
<TONE-2, SAKOT, LOW YA> normalises to <SAKOT, TONE-2, LOW YA>, which
does not match any portion of the regular expression.
Could someone answer this question, please? The USE documentation ("CGJ
handling will need to be updated if USE is modified to support
normalization") still implies that the USE does not respect canonical
equivalence.
Richard.
