<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><!--StartFragment--><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">Note to the IDNABIS Working Group: </span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">During processing of the Last Call responses, the Area Director expressed discomfort with the state of consensus on the use of Latin Small Letter Sharp S and Greek Small Letter Final Sigma. To gain additional input on whether these should remain PVALID, I am sending the letter below to the Unicode Technical Committee for its opinion. <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><br></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; ">vint cerf</div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><br></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; ">------------------</div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><br></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><br></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">Ms.
Lisa Moore<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">Chairman,
Unicode Technical Committee<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">via
email: <a href="mailto:lisam@us.ibm.com">lisam@us.ibm.com</a><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">CC:
<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">Eric
Muller<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">Vice
Chairman, Unicode Technical Committee<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">via
email: <a href="mailto:emuller@adobe.com">emuller@adobe.com</a><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">Mark
Davis<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">President,
Unicode Consortium<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">via
email: <a href="mailto:markdavis@googlle.com">markdavis@googlle.com</a><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">28
November 2010<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">Dear
Ms. Moore:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">I
am writing to you in my role as chairman of the IDNABIS working group,
addressing this request to you as president of the Unicode Consortium. As you
know, treatment of the two characters, Greek Small Letter Final Sigma (U+03C2)
and Latin Small Letter Sharp S (U+00DF) have been the source of considerable
discussion during the IDNABIS Working Group effort on specifying the
IDNA2008 proposed replacement of the IDNA2003 standard for the use of
Unicode in Internationalized Domain Names. Latin Capital Letter Sharp S
(U+1E9E) was added in Unicode version 5.1.0 but recommended rules for its use
were provided as shown below:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">Begin
quote from Unicode Version 5.1.0<o:p></o:p></span></div><p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-bottom:14.0pt;
margin-left:0in;mso-pagination:none;mso-layout-grid-align:none;text-autospace:
none"><span style="font-size:14.0pt;font-family:Helvetica;color:#244FAB"><b>Tailored
Casing Operations</b></span><span style="font-size:14.0pt;font-family:Helvetica"><b><o:p></o:p></b></span></p><p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
margin-left:0in;mso-pagination:none;mso-layout-grid-align:none;text-autospace:
none"><span style="font-family:Helvetica">The Unicode Standard provides default
casing operations. There are circumstances in which the default operations need
to be tailored for specific locales or environments. Some of these tailorings
have data that is in the standard, in the SpecialCasing.txt file, notable for
the Turkish <i>dotted capital I</i></span><span style="font-family:Helvetica"> and
<i>dotless small i</i></span><span style="font-family:Helvetica">. In other
cases, more specialized tailored casing operations may be appropriate. These
include:<o:p></o:p></span></p><div style="margin-top: 0in; margin-right: 0in; margin-left: 0.5in; margin-bottom: 0.0001pt; text-indent: -0.5in; "><span style="font-family:Helvetica">Titlecasing
of IJ at the start of words in Dutch<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0.5in; margin-bottom: 0.0001pt; text-indent: -0.5in; "><span style="font-family:Helvetica">Removal
of accents when uppercasing letters in Greek<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0.5in; margin-bottom: 0.0001pt; text-indent: -0.5in; "><span style="font-family:Helvetica">Uppercasing
U+00DF ( </span><span style="font-family:ArialMT">ß </span><span style="font-family:Helvetica">) LATIN SMALL LETTER SHARP S to the new U+1E9E
LATIN CAPITAL LETTER SHARP S<o:p></o:p></span></div><p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
margin-left:0in;mso-pagination:none;mso-layout-grid-align:none;text-autospace:
none"><span style="font-family:Helvetica">However, these tailorings may or may
not be desired, depending on the implementation in question.<o:p></o:p></span></p><p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
margin-left:0in;mso-pagination:none;mso-layout-grid-align:none;text-autospace:
none"><span style="font-family:Helvetica">In particular, <i>capital sharp s</i></span><span style="font-family:Helvetica"> is intended for typographical representations of
signage and uppercase titles, and other environments where users require the <i>sharp
s</i></span><span style="font-family:Helvetica"> to be preserved in uppercase.
Overall, such usage is rare. In contrast, standard German orthography uses the
string "SS" as uppercase mapping for <i>small sharp s</i></span><span style="font-family:Helvetica">. Thus, with the default Unicode casing
operations, <i>capital sharp s</i></span><span style="font-family:Helvetica">
will lowercase to <i>small sharp s</i></span><span style="font-family:Helvetica">,
but not the reverse: <i>small sharp s</i></span><span style="font-family:Helvetica">
uppercases to "SS". In those instances where the reverse casing
operation is needed, a tailored operation would be required. <o:p></o:p></span></p><p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
margin-left:0in;mso-pagination:none;mso-layout-grid-align:none;text-autospace:
none"><span style="font-family:Helvetica">End quote from Unicode Version 5.1.0<o:p></o:p></span></p><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">In
IDNA2003, Sharp S was mapped to "ss" by means of a casing operation
that mapped lower case Sharp S to uppercase "SS" and then down to
lowercase "ss". Registrations and lookups using the IDNA2003 rules
applied this mechanism. <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">During
the discussions in the IDNABIS Working Group on IDNA2008, a strong consensus
developed around not mapping for example for registration purposes and also for
preserving the property that the IDNA2008-defined A-Label and U-Label forms be
fully symmetric (i.e., convertible into one another without change or
loss). <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><p class="MsoNormal" style="mso-pagination:none;mso-layout-grid-align:none;
text-autospace:none"><span style="font-family:Helvetica">During these same
discussions, a consensus seemed to develop to permit (ie. make
"PVALID" in IDNA2008 parlance) Latin Small Letter Sharp S (U+00DF)
and Greek Small Letter Final Sigma (U+03C2). The recommended casing
actions of Unicode (i.e. toCaseFold) on Sharp S and Final Sigma produce
"ss" in the case of Sharp S and Greek Small Letter Sigma (U+03C3) in
the case of Final Sigma.<o:p></o:p></span></p><p class="MsoNormal" style="mso-pagination:none;mso-layout-grid-align:none;
text-autospace:none"><span style="font-family:Helvetica">To make the lowercase
forms PVALID using the functional rules of IDNA2008, exceptions were
required to overcome the recommended casing mechanics of Unicode (i.e.
application of CaseFolding). <o:p></o:p></span></p><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">Note
that IDNA2008 explicitly permits mapping for User Interface purposes:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; text-indent: 0.5in; "><span style="font-family:Helvetica">a) draft-ietf-idnabis-protocol-17#section-5.2 <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; text-indent: 0.5in; "><span style="font-family:Helvetica">c) draft-ietf-idnabis-rationale-14#section-4.4<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; text-indent: 0.5in; "><span style="font-family:Helvetica">d) draft-ietf-idnabis-rationale-14#section-6<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; text-indent: 0.5in; "><span style="font-family:Helvetica">e) draft-ietf-idnabis-rationale-14#section-7.3<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; text-indent: 0.5in; "><span style="font-family:Helvetica">f) draft-ietf-idnabis-mappings-05 <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; text-indent: 0.5in; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">If
Small Letter Sharp S and Small Letter Final Sigma were to be made DISALLOWED,
these mapping provisions would permit these characters to be handled as a User
Interface matter prior to lookup. <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">Because
the practices of IDNA2003 are in conflict with the proposed practices of
IDNA2008, and because the Last Call discussions have surfaced controversy over
the incorporation of the two lowercase forms in question, I request an
organizational recommendation from UTC as to the treatment of these characters.
Taking into account the prohibition of mapping on registration, which I take to
be firm, and the requirement that A-Label and U-Label forms must be
unambiguously convertible into each other, would the UTC recommend to exclude
the use of Small Letter Sharp S and Small Letter Final Sigma in IDNA2008
by removing their exceptions and making each DISALLOWED?<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">A
prompt response would be much appreciated considering we have delayed reporting
the results of the IETF LAST CALL to the Internet Engineering Steering Group
while this matter is debated.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">Sincerely,<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica"> <o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; "><span style="font-family:Helvetica">Vinton
Cerf<o:p></o:p></span></div>
<div class="MsoNormal"><span style="font-family:Helvetica">Chairman, IDNABIS
Working Group of the Internet Engineering Task Force</span></div>
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