Eszett

[Vint Cerf]

 Mark we have been over this repeatedly and the WG is well aware of the risk
and side effects and has DECIDED to make the character pvalid. Please accept
this. It is the consensus decision. V

------------------------------
 *From*: idna-update-bounces at alvestrand.no <
idna-update-bounces at alvestrand.no>
*To*: Michael Everson <everson at evertype.com>
*Cc*: IDNA update work <idna-update at alvestrand.no>
*Sent*: Mon Jul 20 05:35:05 2009
*Subject*: Re: Eszett

My apologies, I gave the wrong examples. Here are the corrected ones:

If we were starting with a blank slate, it would be feasible to have ß/ẞ
kept separate from ss/SS (although note that the German national standards
body doesn't: the uppercase of ß is SS, which is why they got connected in
the first place in Unicode). Similarly, it would have been possible to
separate σ/ς (again, joined because they have a common uppercase Σ).

*But we are not starting with a clean slate: *we are facing with changes to
an existing widely-deployed standard, over 6 years old, which is a long time
in terms of the web. We have two effective options:
 A. Maintain compatibility with IDNA2003  * URLs* * Result
* *When*  http://www.γιατρός.gr <http://www.xn--mxads7ake1d.gr>
http://www.γιατρόσ.gr <http://www.xn--mxads7ake1d.gr>
http://www.ΓΙΑΤΡΌΣ.gr <http://www.xn--mxads7ake1d.gr>
 http://www.xn--mxads7ake1d.gr<http://www.%CE%B3%CE%B9%CE%B1%CF%84%CF%81%CF%8C%CF%83.gr/>
*always*  http://www.weltfußball.at <http://www.weltfussball.at>
http://www.WELTFUẞBALL.at
http://www.weltfussball.at
http://www.WELTFUSSBALL.at
http://www.weltfussball.at *always*

 B. Deviate from IDNA2003Try to separate them, leaving users with a de-facto
indeterminant mapping. That results in the following:

  * URLs* * Result
* *When*  http://www.γιατρός.gr <http://www.xn--mxads7ake1d.gr>
http://www.xn--mxads7afk1d.gr *sometimes*
http://www.xn--mxads7ake1d.gr<http://www.%CE%B3%CE%B9%CE%B1%CF%84%CF%81%CF%8C%CF%83.gr/>
*sometimes*
  http://www.γιατρόσ.gr <http://www.xn--mxads7ake1d.gr>
http://www.ΓΙΑΤΡΌΣ.gr <http://www.xn--mxads7ake1d.gr>
 http://www.xn--mxads7ake1d.gr<http://www.%CE%B3%CE%B9%CE%B1%CF%84%CF%81%CF%8C%CF%83.gr/>
*always*
  http://www.weltfußball.at <http://www.weltfussball.at>
http://www.WELTFUẞBALL.at
http://www.xn--weltfuball-b4a.at *sometimes*  http://www.weltfussball.at *
sometimes*  http://www.weltfussball.at
http://www.WELTFUSSBALL.at
 http://www.weltfussball.at *always*
 Why would this happen? Well, for some indefinite period time, both IDNA2003
and IDNA2008 clients will exist. So you get on a friend's machine, go to
your bank site, and get to a spoof site. Moreover, in an effort to maintain
compatibility for clients, most client-software will do a dual lookup; first
try one then the other. If someone comes in with an intervening
registration, for a spoof site, then a URL that used to work for you now
leads to the spoof site.

Now perhaps the NICs for de, at, and ch will address ß/ẞ/ss/SS (and the NIC
for gr will address σ/ς/Σ) by bundling or blocking. But bundling or blocking
defeats the purpose of separating them, and there is little reason to think
that .com, .biz, .whatever will all do the same -- not to speak of the many,
many more registries below the top level.
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