I agree. The main backward compatibility change is that without preprocessing a very number of strings break. If someone does do preprocessing -- and we define a uniform mechanism for doing it -- then the differences can be quite small (depending on what the wg decides).<br>
<br>For more information on possible preprocessing, see the rough draft at<i><i> </i></i><a id="publishedDocumentUrl" class="tabcontent" target="_blank" href="http://docs.google.com/Doc?id=dfqr8rd5_51c3nrskcx"><i>http://docs.google.com/Doc?id=dfqr8rd5_51c3nrskcx</i></a><i>.<br>
<br>Mark<br></i><br><div class="gmail_quote">On Tue, Mar 18, 2008 at 9:44 AM, Simon Josefsson <<a href="mailto:simon@josefsson.org">simon@josefsson.org</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Harald Tveit Alvestrand <<a href="mailto:harald@alvestrand.no">harald@alvestrand.no</a>> writes:<br>
<br>
>> I'm assuming IDNABIS won't be (fully) backwards compatible with<br>
>> IDNA2003. That is the impression I have gotten from all discussions so<br>
>> far.<br>
> The only incompatibility so far proposed is that some names valid<br>
> under IDNA2003 will not be valid under IDNA200x, and vice versa. For<br>
> all names that are valid under both proposals, I don't believe any<br>
> change has been proposed.<br>
<br>
When you upgrade the Unicode version, some strings that normalize to one<br>
value under Unicode 3.2 NFKC will not normalize to the same value under<br>
Unicode 5.0. See:<br>
<br>
<a href="http://www.gnu.org/software/libidn/manual/libidn.html#PR29-Functions" target="_blank">http://www.gnu.org/software/libidn/manual/libidn.html#PR29-Functions</a><br>
<a href="http://www.gnu.org/software/libidn/manual/libidn.html#PR29-discussion" target="_blank">http://www.gnu.org/software/libidn/manual/libidn.html#PR29-discussion</a><br>
<br>
I have also noted the discussion around ß. If IDNABIS-ToASCII(ß) != ss<br>
then another backwards incompatible change is made.<br>
<br>
In my comment on the IDNABIS WG charter I suggested that the charter<br>
should say that the IDNABIS output needs to be strongly backwards<br>
compatible. Both Lisa and Sam from the IESG disagreed. My conclusion<br>
is that the WG is entitled to make backwards incompatible changes, and<br>
given the discussions so far that involves using Unicode > 3.2 NFKC and<br>
how ß will be handled, the WG will likely also make backwards<br>
incompatible changes.<br>
<br>
I think a useful output from the WG would be to clarify which backwards<br>
incompatible changes are being made.<br>
<br>
/Simon<br>
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</blockquote></div><br><br clear="all"><br>-- <br>Mark