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+Network Working Group                                          M. Duerst
+Internet-Draft                                       W3C/Keio University
+Expires: December 30, 2002                                  July 1, 2002
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+                  Internationalized Domain Names in URIs
+                          draft-ietf-idn-uri-02
+
+Status of this Memo
+
+    This document is an Internet-Draft and is in full conformance with
+    all provisions of Section 10 of RFC2026.
+
+    Internet-Drafts are working documents of the Internet Engineering
+    Task Force (IETF), its areas, and its working groups.  Note that
+    other groups may also distribute working documents as Internet-
+    Drafts.
+
+    Internet-Drafts are draft documents valid for a maximum of six months
+    and may be updated, replaced, or obsoleted by other documents at any
+    time.  It is inappropriate to use Internet-Drafts as reference
+    material or to cite them other than as "work in progress."
+
+    The list of current Internet-Drafts can be accessed at http://
+    www.ietf.org/ietf/1id-abstracts.txt.
+
+    The list of Internet-Draft Shadow Directories can be accessed at
+    http://www.ietf.org/shadow.html.
+
+    This Internet-Draft will expire on December 30, 2002.
+
+Copyright Notice
+
+    Copyright (C) The Internet Society (2002).  All Rights Reserved.
+
+Abstract
+
+    This document proposes to upgrade the definition of URIs (RFC 2396)
+    [RFC2396] to work consistently with internationalized domain names.
+
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+Duerst                  Expires December 30, 2002               [Page 1]
+
+Internet-Draft                IDNs in URIs                     July 2002
+
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+Table of Contents
+
+    1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
+    2.  URI syntax changes . . . . . . . . . . . . . . . . . . . . . .  3
+    3.  Security considerations  . . . . . . . . . . . . . . . . . . .  5
+    4.  Change Log . . . . . . . . . . . . . . . . . . . . . . . . . .  5
+    4.1 Changes from draft-ietf-idn-uri--01 to draft-ietf-idn-uri-02 .  5
+    4.2 Changes from draft-ietf-idn-uri--00 to draft-ietf-idn-uri-01 .  5
+        References . . . . . . . . . . . . . . . . . . . . . . . . . .  5
+        Author's Address . . . . . . . . . . . . . . . . . . . . . . .  7
+        Full Copyright Statement . . . . . . . . . . . . . . . . . . .  8
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+Duerst                  Expires December 30, 2002               [Page 2]
+
+Internet-Draft                IDNs in URIs                     July 2002
+
+
+1. Introduction
+
+    Internet domain names serve to identify hosts and services on the
+    Internet in a convenient way.  The IETF IDN working group [IDNWG] has
+    been working on extending the character repertoire usable in domain
+    names beyond a subset of US-ASCII.
+
+    One of the most important places where domain names appear are
+    Uniform Resource Identifiers (URIs, [RFC2396], as modified by
+    [RFC2732]).  However, in the current definition of the generic URI
+    syntax, the restrictions on domain names are 'hard-coded'.  In
+    Section 2, this document relaxes these restrictions by updating the
+    syntax, and defines how internationalized domain names are encoded in
+    URIs.
+
+    The syntax in this document has been choosen to further increase the
+    uniformity of URI syntax, which is a very important principle of
+    URIs.
+
+    In practice, escaped domanin names should be used as rarely as
+    possible.  Wherever possible, the actual characters in
+    Internationalized Domain Names should be preserved as long as
+    possible by using IRIs [IRI] rather than URIs, and only converting to
+    URIs and then to ACE-encoded [IDNA] domain names (or ideally directly
+    to ACE-encoding without even using URIs) when resolving the IRI.
+    Also, this document does in no way exclude the use of ACE encoding
+    directly in an URI domain name part.  ACE encoding may be used
+    directly in an URI domain name part if this is considered necessary
+    for interoperability.
+
+    Please note that even with the definition of URIs in [RFC2396], some
+    URIs can already contain host names with escaped characters.  For
+    example, mailto:example@w%33.org is legal per [RFC2396] because the
+    mailto: URI scheme does not follow the generic syntax of [RFC2396].
+
+2. URI syntax changes
+
+    The syntax of URIs [RFC2396] currently contains the following rules
+    relevant to domain names:
+
+           hostname      = *( domainlabel "." ) toplabel [ "." ]
+           domainlabel   = alphanum | alphanum *( alphanum | "-" ) alphanum
+           toplabel      = alpha | alpha *( alphanum | "-" ) alphanum
+
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+Duerst                  Expires December 30, 2002               [Page 3]
+
+Internet-Draft                IDNs in URIs                     July 2002
+
+
+    The later two rules are changed as follows:
+
+           domainlabel   = anchar | anchar *( anchar | "-" ) anchar
+           toplabel      = achar | achar *( anchar | "-" ) anchar
+
+    and the following rules are added:
+
+    		 anchar        = alphanum | escaped
+    		 achar         = alpha | escaped
+
+    Characters outside the repertoire (alphanum) are encoded by first
+    encoding the characters in UTF-8 [RFC 2279], resulting in a sequence
+    of octets, and then escaping these octets according to the rules
+    defined in [RFC2396].
+
+    Using UTF-8 assures that this encoding interoperates with IRIs [IRI].
+    It is also aligned with the recommendations in [RFC2277] and
+    [RFC2718], and is consistent with the URN syntax [RFC2141] as well as
+    recent URL scheme definitions that define encodings of non-ASCII
+    characters based on UTF-8 (e.g., IMAP URLs [RFC2192] and POP URLs
+    [RFC2384]).
+
+    The above syntax rules permit for domain names that are neither
+    permitted as US-ASCII only domain names nor as internationalized
+    domain names.  However, such syntax should never be used, and will
+    always be rejected by resolvers.  For US-ASCII only domain names, the
+    syntax rules in [RFC2396] are relevant.  For example, http://
+    www.w%33.org is legal, because the corresponding 'w3' is a legal
+    'domainlabel' according to [RFC2396].  However, http://
+    %2a.example.org is illegal because the corresponding '*' is not a
+    legal 'domainlabel' according to [RFC2396].  For domain names
+    containing non-ASCII characters, the legal domain names are those for
+    which the ToASCII operation ([IDNA], [Nameprep]; using the unescaped
+    UTF-8 values as input) is successful.
+
+    For consistency in comparison operations and for interoperability
+    with older software, the following should be noted: 1) US-ASCII
+    characters in domain names should not be escaped.  2) Because of the
+    principle of syntax uniformity for URIs, it is always more prudent to
+    take into account the possibility that US-ASCII characters are
+    escaped.
+
+    The work of the IDN WG includes some procedures for name preparation
+    [Nameprep].  Before encoding an internationalized domain name in an
+    URI, this preparation step SHOULD be applied.  However, the URI
+    resolver MUST also apply any steps required as part of domain name
+    resolution by [IDNA].
+
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+Duerst                  Expires December 30, 2002               [Page 4]
+
+Internet-Draft                IDNs in URIs                     July 2002
+
+
+3. Security considerations
+
+    The security considerations of [RFC2396] and those applying to
+    internationalized domain names apply.  There may be an increased
+    potential to smuggle escaped US-ASCII-based domain names across
+    firewalls, although because of the uniform syntax principle for URIs,
+    such a potential is already existing.
+
+4. Change Log
+
+4.1 Changes from draft-ietf-idn-uri--01 to draft-ietf-idn-uri-02
+
+    Moved change log to back
+
+    Changed to only change URIs; IRI syntax updated directly in IRI
+    draft.
+
+    Removed syntax restriction on %hh in the US-ASCII part, but made
+    clear that restrictions to domain names apply.
+
+    Made clear that escaped domain names in URIs should only be an
+    intermediate representation.
+
+    Gave example of mailto: as already allowing escaped host names.
+
+4.2 Changes from draft-ietf-idn-uri--00 to draft-ietf-idn-uri-01
+
+    Changed requirement for URI/IRI resolvers from MUST to SHOULD
+
+    Changed IRI syntax slightly (ichar -> idchar, based on changes in
+    [IRI])
+
+    Various wording changes
+
+References
+
+    [IDNA]      Faltstrom, P., Hoffman, P. and A. Costello,
+                "Internationalizing Domain Names in Applications (IDNA)",
+                draft-ietf-idn-idna-09.txt (work in progress), May 2002,
+                <http://www.ietf.org/internet-drafts/draft-ietf-idn-idna-
+                09.txt>.
+
+    [IDNWG]     "IETF Internationalized Domain Name (idn) Working Group".
+
+    [IRI]       Duerst, M. and M. Suignard, "Internationalized Resource
+                Identifiers (IRI)", draft-duerst-iri-01 (work in
+                progress), July 2002.
+
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+
+Internet-Draft                IDNs in URIs                     July 2002
+
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+    [ISO10646]  International Organization for Standardization,
+                "Information Technology - Universal Multiple-Octet Coded
+                Character Set (UCS) - Part 1: Architecture and Basic
+                Multilingual Plane", ISO Standard 10646-1, October 2000.
+
+    [Nameprep]  Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep
+                Profile for Internationalized Domain Names", draft-ietf-
+                idn-nameprep-10.txt (work in progress), May 2002, <http:/
+                /www.ietf.org/internet-drafts/draft-ietf-idn-nameprep-
+                10.txt>.
+
+    [RFC2119]   Bradner, S., "Key words for use in RFCs to Indicate
+                Requirement Levels", BCP 14, RFC 2119, March 1997.
+
+    [RFC2141]   Moats, R., "URN Syntax", RFC 2141, May 1997.
+
+    [RFC2192]   Newman, C., "IMAP URL Scheme", RFC 2192, September 1997.
+
+    [RFC2277]   Alvestrand, H., "IETF Policy on Character Sets and
+                Languages", BCP 18, RFC 2277, January 1998.
+
+    [RFC2279]   Yergeau, F., "UTF-8, a transformation format of ISO
+                10646", RFC 2279, January 1998.
+
+    [RFC2384]   Gellens, R., "POP URL Scheme", RFC 2384, August 1998.
+
+    [RFC2396]   Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
+                Resource Identifiers (URI): Generic Syntax", RFC 2396,
+                August 1998.
+
+    [RFC2640]   Curtin, B., "Internationalization of the File Transfer
+                Protocol", RFC 2640, July 1999.
+
+    [RFC2718]   Masinter, L., Alvestrand, H., Zigmond, D. and R. Petke,
+                "Guidelines for new URL Schemes", RFC 2718, November
+                1999.
+
+    [RFC2732]   Hinden, R., Carpenter, B. and L. Masinter, "Format for
+                Literal IPv6 Addresses in URL's", RFC 2732, December
+                1999.
+
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+Duerst                  Expires December 30, 2002               [Page 6]
+
+Internet-Draft                IDNs in URIs                     July 2002
+
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+Author's Address
+
+    Martin Duerst
+    W3C/Keio University
+    5322 Endo
+    Fujisawa  252-8520
+    Japan
+
+    Phone: +81 466 49 1170
+    Fax:   +81 466 49 1171
+    EMail: duerst@w3.org
+    URI:   http://www.w3.org/People/D%C3%BCrst/
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+Duerst                  Expires December 30, 2002               [Page 7]
+
+Internet-Draft                IDNs in URIs                     July 2002
+
+
+Full Copyright Statement
+
+    Copyright (C) The Internet Society (2002).  All Rights Reserved.
+
+    This document and translations of it may be copied and furnished to
+    others, and derivative works that comment on or otherwise explain it
+    or assist in its implementation may be prepared, copied, published
+    and distributed, in whole or in part, without restriction of any
+    kind, provided that the above copyright notice and this paragraph are
+    included on all such copies and derivative works.  However, this
+    document itself may not be modified in any way, such as by removing
+    the copyright notice or references to the Internet Society or other
+    Internet organizations, except as needed for the purpose of
+    developing Internet standards in which case the procedures for
+    copyrights defined in the Internet Standards process must be
+    followed, or as required to translate it into languages other than
+    English.
+
+    The limited permissions granted above are perpetual and will not be
+    revoked by the Internet Society or its successors or assigns.
+
+    This document and the information contained herein is provided on an
+    "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
+    TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
+    BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
+    HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
+    MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
+
+Acknowledgement
+
+    Funding for the RFC Editor function is currently provided by the
+    Internet Society.
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+
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