Network Working Group D. Kohn
Internet-Draft Skymoon Ventures
Obsoletes: 1036 (if approved) February 1, 2003
Expires: August 2, 2003
News Article Format
draft-kohn-news-article-00.txt
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 August 2, 2003.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document defines the format and procedures for interchange of
network news articles. It updates and obsoletes RFC 1036, in
particular adding support for internationalization of headers and
message bodies and multimedia support in message bodies. It does
this in a manner designed to maximize backward compatibility with
mail and news servers, gateways, and user agents.
Network news articles resemble mail messages but are broadcast to
potentially-large audiences, using a flooding algorithm that
propagates one copy to each interested host (or group thereof),
typically stores only one copy per host, and does not require any
central administration or systematic registration of interested
Kohn Expires August 2, 2003 [Page 1]
Internet-Draft News Article Format February 2003
users. Network news originated as the medium of communication for
Usenet, circa 1980. Since then Usenet has grown explosively, and many
Internet sites participate in it. In addition, the news technology is
now in widespread use for other purposes, on the Internet and
elsewhere.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Requirements notation . . . . . . . . . . . . . . . . . . . 3
1.3 Syntax notation . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Structure of this document . . . . . . . . . . . . . . . . . 3
2. Format . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Base . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 MIME Conformance . . . . . . . . . . . . . . . . . . . . . . 4
3. Headers . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1 Mandatory headers . . . . . . . . . . . . . . . . . . . . . 5
3.2 News headers . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2.1 Newsgroups . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2.2 Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2.3 Followup-To . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2.4 Expires . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3 Other headers . . . . . . . . . . . . . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . 8
Normative References . . . . . . . . . . . . . . . . . . . . 9
Informative References . . . . . . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . 10
A. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
Intellectual Property and Copyright Statements . . . . . . . 12
Kohn Expires August 2, 2003 [Page 2]
Internet-Draft News Article Format February 2003
1. Introduction
1.1 Scope
"Netnews" is a set of protocols for generating, storing and
retrieving news "articles" (which resemble email messages) and for
exchanging them amongst a readership which is potentially widely
distributed. It is organized around "newsgroups", with the
expectation that each reader will be able to see all articles posted
to each newsgroup in which she participates. These protocols most
commonly use a flooding algorithm which propagates copies throughout
a network of participating servers. Typically, only one copy is
stored per server, and each server makes it available on demand to
readers able to access that server.
The predecessor to this document [RFC1036] said that: "In any
situation where this standard conflicts with the Internet [email
standard, the latter] should be considered correct and this standard
in error." The basic philosophy of this document follows that
previous convention, so as to standardize news article syntax firmly
in the context of email syntax. Further, this document uses a cite
by reference methodology, rather than trying to repeat the contents
of other standards, which could otherwise result in subtle
differences and interoperability challenges. Although this document
is as a result rather short, it requires complete understanding and
implementation of the normative references to be compliant.
This document specifies only the syntax of compliant news articles. A
companion document will be necessary to specify the policy
requirements and recommendations of news agents, servers, and
gateways.
1.2 Requirements notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
1.3 Syntax notation
Headers defined in this specification use the Augmented Backus-Naur
Form (ABNF) notation specified in [RFC2234] and many constructs
defined in [RFC2822].
1.4 Structure of this document
Section 2 defines the format of news articles. Section 3 defines some
additional headers necessary for the netnews environment.
Kohn Expires August 2, 2003 [Page 3]
Internet-Draft News Article Format February 2003
2. Format
2.1 Base
News articles MUST conform to the "legal to generate syntax"
specified in Section 3 of [RFC2822], except for the different
requirement of mandatory headers as specified in Section 3.1. News
agents SHOULD also support the obsolete syntax specified in Section 4
of [RFC2822], particularly to support old news messages and gatewayed
obsolete mail messages, but they MUST NOT generate such syntax.
2.2 MIME Conformance
News agents MUST meet the definition of MIME-conformance in
[RFC2049]. Note that this requires support for [RFC2047]
internationalization (i18n) of headers. In addition, news agents
MUST support the i18n extensions for parameters and language tagging
specified in [RFC2231].
Section 2.10 of [RFC2049] describes the display of encoded-words.
This document adds an additional requirement that for encoded words
using the UTF-8 charset, the news agent MUST at least be able to
display the characters which are also in the US-ASCII charset.
News agents conformant with this document MUST also support receipt
(and automatic reassembly) of message/partial MIME messages, as
specified in Section 5.2.2 of [RFC2046]. News agents SHOULD support
generation of message/partial articles for excessively large
articles.
The one change from [RFC2047] is that while Section 3 of that
document recommends that "members of the ISO-8859-* series be used in
preference to other character sets", this document specifies that
news agents SHOULD use UTF-8 as the charset for encoded words. Among
other things, this is conformant with the IETF recommendations of
[RFC2277].
Kohn Expires August 2, 2003 [Page 4]
Internet-Draft News Article Format February 2003
3. Headers
3.1 Mandatory headers
Each news article conformant with this specification MUST have
exactly one of each of the following headers: Date, From, Message-ID,
Subject, Newsgroups, and Path. The first 4 are specified in
[RFC2822].
3.2 News headers
3.2.1 Newsgroups
The Newsgroups header specifies which newsgroup(s) the article is
posted to:
newsgroups = "Newsgroups: " newsgroup-list CRLF
newsgroup-list = newsgroup-name *( "," [FWS] newsgroup-name )
newsgroup-name = component *( "." component ) ; 71 character max
component = plain-component / encoded-comp
plain-component = component-start *29component-rest
component-start = lowercase / DIGIT
lowercase = %x61-7A ; a-z
component-rest = component-start / "+" / "-" / "_"
encoded-comp = ace-prefix 1*25ldh
ace-prefix = "zz--"
ldh = lowercase / DIGIT / "-"
A newsgroup name consists of one or more components separated by
periods, with no more than 71 characters total. Each component
consists of less than 30 lowercase letters and digits, or is an
encoded component. The order of newsgroup names in the Newsgroups
header is not significant.
3.2.1.1 Encoded components
Encoding of i18n newsgroup names follows the general approach laid
out in [IDNA]. Encoded components are strings of Unicode characters
Kohn Expires August 2, 2003 [Page 5]
Internet-Draft News Article Format February 2003
that have been normalized using [nameprep] and encoded using
[punycode]. The main difference from [IDNA] is that this
specification limits encoded components to 30 characters, not 63.
With the 4 character ACE prefix, that means that the output of
punycode is limited to 26 characters.
This example encodes the newsgroup name that would be displayed as
"test.3<nen>B<gumi><kinpachi><sensei>.misc", where the middle
component consists of the Unicode string U+0033 U+5E74 U+0042 U+7D44
U+91D1 U+516B U+5148 U+751F. Punycode encodes that string as
"3B-ww4c5e180e575a65lsy2b". So, the resulting newsgroup name, which
has been encoded so as to comply with this document, is
"test.zz--3B-ww4c5e180e575a65lsy2b.misc".
3.2.2 Path
The Path-header shows the route taken by a message since its entry
into the Netnews system.
path = "Path: " path-content CRLF
path-content = [FWS] *( path-host [FWS] path-delimiter [FWS] )
tail-entry [FWS]
path-host = ( ALPHA / DIGIT )
*( ALPHA / DIGIT / "-" / "." / ":" / "_" )
path-delimiter = "/" / "?" / "%" / "," / "!"
tail-entry = path-identity
3.2.3 Followup-To
The Followup-To header specifies to which newsgroup(s) followups
should be posted.
followup-to = "Followup-To: " followup-value CRLF
followup-value = newsgroups-list / poster-text
poster-text = [FWS] %x70.6F.73.74.65.72 [FWS]
; "poster" in lower-case
The syntax is the same as that of the Newsgroups content, with the
exception that the magic word "poster" means that followups should be
mailed to the article's reply address rather than posted. In the
absence of Followup-To, the default newsgroup(s) for a followup are
those in the Newsgroups header.
Kohn Expires August 2, 2003 [Page 6]
Internet-Draft News Article Format February 2003
3.2.4 Expires
The Expires header content specifies a date and time when the article
is deemed to be no longer useful and should be removed ("expired").
expires = "Expires: " date-time CRLF
The content syntax is the same as that of the Date content. In the
absence of Expires, the default is decided by the administrators of
each host the article reaches, who MAY also restrict the extent to
which the Expires header is honored.
3.3 Other headers
Add info on References, Control, Distribution, Summary, Approved,
Lines, Xref, Supercedes, Also-Control, See-Also, Article-Names, and
Article-Updates.
Kohn Expires August 2, 2003 [Page 7]
Internet-Draft News Article Format February 2003
4. Security Considerations
The News Article Format specified in this document does not provide
any security services, such as confidentiality, authentication of
sender, or non-forgery. Instead, such services need to be layered
above, using such protocols as S/MIME [RFC2633] or PGP/MIME
[RFC3156], or below, using secure versions of news transport
protocols. Additionally, several currently non-standardized
protocols [PGPVERIFY] will hopefully be standardized in the near
future.
Kohn Expires August 2, 2003 [Page 8]
Internet-Draft News Article Format February 2003
Normative References
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
November 1996.
[RFC2047] Moore, K., "MIME (Multipurpose Internet Mail Extensions)
Part Three: Message Header Extensions for Non-ASCII Text",
RFC 2047, November 1996.
[RFC2049] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Five: Conformance Criteria and
Examples", RFC 2049, November 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded
Word Extensions: Character Sets, Languages, and
Continuations", RFC 2231, November 1997.
[RFC2234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[RFC2822] Resnick, P., "Internet Message Format", RFC 2822, April
2001.
[nameprep]
Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep
Profile for Internationalized Domain Names",
draft-ietf-idn-nameprep-11 (work in progress), June 2002.
[punycode]
Costello, A., "Punycode:A Bootstring encoding of Unicode
for IDNA", Internet-Draft punycode, October 2002.
Kohn Expires August 2, 2003 [Page 9]
Internet-Draft News Article Format February 2003
Informative References
[IDNA] Hoffman, P., Faltstrom, P. and A. Costello,
"Internationalizing Domain Names In Applications (IDNA)",
draft-ietf-idn-idna-14 (work in progress), October 2002.
[PGPVERIFY]
Lawrence, D., "PGPverify <ftp://ftp.isc.org/pub/
pgpcontrol/README.html>", June 1999.
[RFC1036] Horton, M. and R. Adams, "Standard for interchange of
USENET messages", RFC 1036, December 1987.
[RFC2277] Alvestrand, H., "IETF Policy on Character Sets and
Languages", BCP 18, RFC 2277, January 1998.
[RFC2633] Ramsdell, B., "S/MIME Version 3 Message Specification",
RFC 2633, June 1999.
[RFC3156] Elkins, M., Del Torto, D., Levien, R. and T. Roessler,
"MIME Security with OpenPGP", RFC 3156, August 2001.
Author's Address
Dan Kohn
Skymoon Ventures
3045 Park Boulevard
Palo Alto, California 94306
USA
Phone: +1-650-327-2600
EMail: dan@dankohn.com
URI: http://www.dankohn.com/
Kohn Expires August 2, 2003 [Page 10]
Internet-Draft News Article Format February 2003
Appendix A. Acknowledgements
Portions of this text were taken from "son-of-1036" by Henry Spencer
and other portions from a draft by Charles Lindsay. Comments on
ietf-822@imc.org inspired this approach. The idea of
punycode-encoded newsgroups was suggested in a draft by Claus
Faerber.
Kohn Expires August 2, 2003 [Page 11]
Internet-Draft News Article Format February 2003
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
Full Copyright Statement
Copyright (C) The Internet Society (2003). 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 assignees.
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
Kohn Expires August 2, 2003 [Page 12]
Internet-Draft News Article Format February 2003
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.
Kohn Expires August 2, 2003 [Page 13]