non-ASCII dots

Erik van der Poel erikv at
Sun Mar 22 18:51:53 CET 2009

Another question from the summary:

> A. Multiple characters are allowed as "dots" in domain names under
> IDNA2003 and presumably under IDNAV2. This is a general problem for
> all versions of IDNA but may be exacerbated by the variants for "dots"
> that are permitted under IDNA2003 and IDNAv2. What is the WG view?

In my view, non-ASCII dots should never have been allowed in IDNA2003.
However, now that many IDNA2003 implementations have been distributed
to users and a few stored domain names use these non-ASCII dots, some
may feel that we have to support them (forever).

Having said that, I am quite concerned about adding yet another
non-ASCII dot in IDNAv2 (U+2CFE COPTIC FULL STOP) because IDNA2003
includes a flag that allows for the lookup of unassigned (in Unicode
3.2) characters. Such applications would not only fail to case-fold
post-Unicode-3.2 characters correctly, they would fail to divide the
full domain name into individual labels, and since DNS labels are
"owned" by different owners, this just seems like an invitation to
further problems.

In my view, the dot is a keyboard and UI issue. Of course, it would be
nice if we could push ALL mappings out to the keyboard and UI, but, to
use one of John's favorite words, this may be "unrealistic". ;-)


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