Internet DRAFT - draft-flanagan-nonascii
draft-flanagan-nonascii
Internet Engineering Task Force H. Flanagan, Ed.
Internet-Draft RFC Editor
Intended status: Informational November 18, 2015
Expires: May 21, 2016
The Use of Non-ASCII Characters in RFCs
draft-flanagan-nonascii-06
Abstract
In order to support the internationalization of protocols and a more
diverse Internet community, the RFC Series must evolve to allow for
the use of non-ASCII characters in RFCs. While English remains the
required language of the Series, the encoding of future RFCs will be
in UTF-8, allowing for a broader range of characters than typically
used in the English language. This document describes the RFC Editor
requirements and guidance regarding the use of non-ASCII characters
in RFCs.
This document updates RFC 7322.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on May 21, 2016.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Basic requirements . . . . . . . . . . . . . . . . . . . . . 3
3. Rules for the use of non-ASCII characters . . . . . . . . . . 3
3.1. General usage throughout a document . . . . . . . . . . . 4
3.2. Authors, Contributors, and Acknowledgments . . . . . . . 4
3.3. Company Names . . . . . . . . . . . . . . . . . . . . . . 5
3.4. Body of the document . . . . . . . . . . . . . . . . . . 5
3.5. Tables . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.6. Code components . . . . . . . . . . . . . . . . . . . . . 8
3.7. Bibliographic text . . . . . . . . . . . . . . . . . . . 8
3.8. Keywords and Citation Tags . . . . . . . . . . . . . . . 9
3.9. Address Information . . . . . . . . . . . . . . . . . . . 9
4. Normalization Forms . . . . . . . . . . . . . . . . . . . . . 9
5. XML Markup . . . . . . . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Internationalization Considerations . . . . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 10
9. Change log - to be removed by the RFC Editor . . . . . . . . 10
9.1. -04 to -05 . . . . . . . . . . . . . . . . . . . . . . . 10
9.2. -04 to -05 . . . . . . . . . . . . . . . . . . . . . . . 10
9.3. -02 to -04 . . . . . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
For much of the history of the RFC Series, the character encoding
used for RFCs has been ASCII [ANSI.X3-4.1986]. This was a sensible
choice at the time: the language of the Series has always been
English, a language that primarily uses ASCII-encoded characters
(ignoring for a moment words borrowed from more richly decorated
alphabets); and, ASCII is the "lowest common denominator" for
character encoding, making cross-platform viewing trivial.
There are limits to ASCII, however, that hinder its continued use as
the exclusive character encoding for the Series. The increasing need
for easily readable, internationalized content suggests it is time to
allow non-ASCII characters in RFCs where necessary. To support this
move away from ASCII, RFCs will switch to supporting UTF-8 as the
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default character encoding and allow support for a broad range of
Unicode character support. [UnicodeCurrent] Note that the RFC
Editor may reject any codepoint that does not render adequately in
enough formats or on in enough rendering engines using the current
tooling.
Given the continuing goal of maximum readability across platforms,
the use of non-ASCII characters should be limited in a document to
only where necessary within the text. This document describes the
rules under which non-ASCII characters may be used in an RFC. These
rules will be applied as the necessary changes are made to submission
checking and editorial tools.
This document updates the RFC Style Guide [RFC7322].
The details described in this document are expected to change based
on experience gained in implementing the RFC production center's
toolset. Revised documents will be published capturing those changes
as the toolset is completed. Other implementers must not expect
those changes to remain backwards-compatible with the details
described this document.
2. Basic requirements
Two fundamental requirements inform the guidance and examples
provided in this document. They are:
o Searches against RFC indexes and database tables need to return
expected results and support appropriate Unicode string matching
behaviors;
o RFCs must be able to display correctly across a wide range of
readers and browsers. People whose system does not have the fonts
needed to display a particular RFC need to be able to read the
various publication formats and the XML correctly in order to
understand and implement the information described in the
document.
3. Rules for the use of non-ASCII characters
This section describes the guidelines for the use of non-ASCII
characters in the header, body, and reference sections of an RFC. If
the RFC Editor identifies areas where the use of non-ASCII characters
negatively impacts the readability of the text, they will request
alternate text.
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The RFC Editor may, in cases of entire words represented in non-ASCII
characters, ask for a set of reviewers to verify the meaning,
spelling, characters, and grammar of the text.
3.1. General usage throughout a document
Where the use of non-ASCII characters is purely as part of an example
and not otherwise required for correct protocol operation, escaping
the non-ASCII character is not required. Note, however, that as the
language of the RFC Series is English, the use of non-ASCII
characters is based on the spelling of words commonly used in the
English language following the guidance in the Merriam-Webster
dictionary [MerrWeb].
The RFC Editor will use the primary spelling listed in that
dictionary by default.
Example of non-ASCII characters that do not require escaping
[RFC4475]:
This particular response contains unreserved and non-ascii
UTF-8 characters.
This response is well formed. A parser must accept this message.
Message Details : unreason
SIP/2.0 200 = 2**3 * 5**2 но сто девяносто девять - простое
Via: SIP/2.0/UDP 192.0.2.198;branch=z9hG4bK1324923
Call-ID: unreason.1234ksdfak3j2erwedfsASdf
CSeq: 35 INVITE
From: sip:user@example.com;tag=11141343
To: sip:user@example.edu;tag=2229 Content-Length: 154
Content-Type: application/sdp
3.2. Authors, Contributors, and Acknowledgments
Person names may appear in several places within an RFC. In all
cases, valid Unicode is required. For names that include non-ASCII
characters, an author-provided, ASCII-only identifier is required to
assist in search and indexing of the document.
Example for the header:
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Network Working Group L. Daigle
Request for Comments: 2611 Thinking Cat Enterprises
BCP: 33 D. van Gulik
Category: Best Current Practice ISIS/CEO, JRC Ispra
R. Iannella
DSTC Pty Ltd
P. Faeltstroem (P. Faltstrom)
Tele2/Swipnet
June 1999
Example for the Acknowledgements:
OLD: The following people contributed significant text to early
versions of this draft: Patrik Faltstrom, William Chan, and Fred
Baker.
PROPOSED/NEW: The following people contributed significant text to
early versions of this draft: Patrik Faeltstroem (Patrik Faltstrom),
陈智昌 (William Chan), and Fred Baker.
3.3. Company Names
Company names may appear in several places within an RFC. The rules
for company names follow similar guidance to that of person names.
Valid Unicode is required. For company names that include non-ASCII
characters, an ASCII-only identifier is required to assist in search
and indexing of the document.
3.4. Body of the document
When the mention of non-ASCII characters is required for correct
protocol operation and understanding, the characters' Unicode
character name or code point MUST be included in the text.
o Non-ASCII characters will require identifying the Unicode code
point.
o Use of the actual UTF-8 character (e.g., Δ) is encouraged so
that a reader can more easily see what the character is, if their
device can render the text.
o The use of the Unicode character names like "INCREMENT" in
addition to the use of Unicode code points is also encouraged.
When used, Unicode character names should be in all capital
letters.
Examples:
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OLD [RFC7564]:
However, the problem is made more serious by introducing the full
range of Unicode code points into protocol strings. For example,
the characters U+13DA U+13A2 U+13B5 U+13AC U+13A2 U+13AC U+13D2 from
the Cherokee block look similar to the ASCII characters "STPETER" as
they might appear when presented using a "creative" font family.
NEW/ALLOWED:
However, the problem is made more serious by introducing the full
range of Unicode code points into protocol strings. For example,
the characters U+13DA U+13A2 U+13B5 U+13AC U+13A2 U+13AC U+13D2
(ᏚᎢᎵᎬᎢᎬᏒ) from the Cherokee block look similar to the ASCII
characters "STPETER" as they might appear when presented using a
"creative" font family.
ALSO ACCEPTABLE:
However, the problem is made more serious by introducing the full
range of Unicode code points into protocol strings. For example,
the characters "ᏚᎢᎵᎬᎢᎬᏒ" (U+13DA U+13A2 U+13B5 U+13AC U+13A2
U+13AC U+13D2) from the Cherokee block look similar to the ASCII
characters "STPETER" as they might appear when presented using a
"creative" font family.
Example of proper identification of Unicode characters in an RFC:
Acceptable:
o Temperature changes in the Temperature Control Protocol are
indicated by the U+2206 character.
Preferred:
1. Temperature changes in the Temperature Control Protocol are
indicated by the U+2206 character ("Δ").
2. Temperature changes in the Temperature Control Protocol are
indicated by the U+2206 character (INCREMENT).
3. Temperature changes in the Temperature Control Protocol are
indicated by the U+2206 character ("Δ", INCREMENT).
4. Temperature changes in the Temperature Control Protocol are
indicated by the U+2206 character (INCREMENT, "Δ").
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5. Temperature changes in the Temperature Control Protocol are
indicated by the "Delta" character "Δ" (U+2206).
6. Temperature changes in the Temperature Control Protocol are
indicated by the character "Δ" (INCREMENT, U+2206).
Which option of (1), (2), (3), (4), (5), or (6) is preferred may
depend on context and the specific character(s) in question. All are
acceptable within an RFC. BCP 137, "ASCII Escaping of Unicode
Character" describes the pros and cons of different options for
identifying Unicode characters in an ASCII document BCP137 [RFC5137].
3.5. Tables
Tables follow the same rules for identifiers and characters as in
"Section 3.4. Body of the document". If it is sensible (i.e., more
understandable for a reader) for a given document to have two tables
-- one including the identifiers and non-ASCII characters and a
second with just the non-ASCII characters -- that will be allowed on
a case-by-case basis.
Original text from "Preparation, Enforcement, and Comparison of
Internationalized Strings Representing Usernames and Passwords"
[RFC7613].
Table 3: A sample of legal passwords
+------------------------------------+------------------------------+
| # | Password | Notes |
+------------------------------------+------------------------------+
| 12| <correct horse battery staple> | ASCII space is allowed |
+------------------------------------+------------------------------+
| 13| <Correct Horse Battery Staple> | Different from example 12 |
+------------------------------------+------------------------------+
| 14| <πßå> | Non-ASCII letters are OK |
| | | (e.g., GREEK SMALL LETTER |
| | | PI, U+03C0) |
+------------------------------------+------------------------------+
| 15| <Jack of ♦s> | Symbols are OK (e.g., BLACK |
| | | DIAMOND SUIT, U+2666) |
+------------------------------------+------------------------------+
| 16| <foo bar> | OGHAM SPACE MARK, U+1680, is |
| | | mapped to U+0020 and thus |
| | | the full string is mapped to |
| | | <foo bar> |
+------------------------------------+------------------------------+
Preferred text:
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Table 3: A sample of legal passwords
+------------------------------------+------------------------------+
| # | Password | Notes |
+------------------------------------+------------------------------+
| 12| <correct horse battery staple> | ASCII space is allowed |
+------------------------------------+------------------------------+
| 13| <Correct Horse Battery Staple> | Different from example 12 |
+------------------------------------+------------------------------+
| 14| <πss๗> | Non-ASCII letters are OK |
| | | (e.g., GREEK SMALL LETTER |
| | | PI, U+03C0; LATIN SMALL |
| | | LETTER SHARP S, U+00DF; THAI |
| | | DIGIT SEVEN, U+0E57) |
+------------------------------------+------------------------------+
| 15| <Jack of ♦s> | Symbols are OK (e.g., BLACK |
| | | DIAMOND SUIT, U+2666) |
+------------------------------------+------------------------------+
| 16| <foo bar> | OGHAM SPACE MARK, U+1680, is |
| | | mapped to U+0020 and thus |
| | | the full string is mapped to |
| | | <foo bar> |
+------------------------------------+------------------------------+
3.6. Code components
The RFC Editor encourages the use of the U+ notation except within a
code component where you must follow the rules of the programming
language in which you are writing the code.
3.7. Bibliographic text
The reference entry must be in English; whatever subfields are
present must be available in ASCII-encoded characters. As long as
good sense is used, the reference entry may also include non-ASCII
characters at the author's discretion and as provided by the author.
The RFC Editor may request a review of the non-ASCII reference entry.
This applies to both normative and informative references.
Example:
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[GOST3410] "Information technology. Cryptographic data security.
Signature and verification processes of [electronic]
digital signature.", GOST R 34.10-2001, Gosudarstvennyi
Standard of Russian Federation, Government Committee of
Russia for Standards, 2001. (In Russian)
Allowable addition to the above citation:
"Информационная технология. Криптографическая защита
информации. Процессы формирования и проверки
электронной цифровой подписи", GOST R 34.10-2001,
Государственный стандарт Российской Федерации, 2001.
3.8. Keywords and Citation Tags
Keywords and citation tags must be ASCII only.
3.9. Address Information
The purpose of providing address information, either postal or
e-mail, is to assist readers of an RFC to contact the author or
authors. Authors may include the official postal address as
recognized by their company or local postal service without
additional non-ASCII character escapes. If the email address
includes non-ASCII characters and is a valid email address at the
time of publication, non-ASCII character escapes are not required.
4. Normalization Forms
Authors should not expect normalization forms to be preserved. If a
particular normalization form is expected, note that in the text of
the RFC.
5. XML Markup
As described above, use of non-ASCII characters in areas such as
email, company name, addresses, and name is allowed. In order to
make it easier for code to identify the appropriate ASCII
alternatives, authors must include an "ascii" attribute to their XML
markup when an ASCII alternative is required. See
[I-D.hoffman-xml2rfc] for more detail on how to tag ASCII
alternatives.
6. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
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7. Internationalization Considerations
The ability to use non-ASCII characters in RFCs in a clear and
consistent manner will improve the ability to describe
internationalized protocols and will recognize the diversity of
authors. However, the goal of readability will override the use of
non-ASCII characters within the text.
8. Security Considerations
Valid Unicode that matches the expected text must be verified in
order to preserve expected behavior and protocol information.
9. Change log - to be removed by the RFC Editor
9.1. -04 to -05
Keywords: expanded section to include citation tags.
Internationalization considerations: reiterated that the use of non-
ASCII characters is not automatically guaranteed.
9.2. -04 to -05
Introduction: added statement regarding document subject to change.
Tables: added example.
Code: removed placeholder for example.
9.3. -02 to -04
Introduction and Abstract: change to be clearer about what/why non-
ASCII characters are being allowed.
XML Markup: section added.
10. References
[ANSI.X3-4.1986]
American National Standards Institute, "Coded Character
Set - 7-bit American Standard Code for Information
Interchange", ANSI X3.4, 1986.
[I-D.hoffman-xml2rfc]
Hoffman, P., "The 'XML2RFC' version 3 Vocabulary", draft-
hoffman-xml2rfc-23 (work in progress), September 2015.
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[MerrWeb] Merriam-Webster,Inc., "Merriam-Webster's Collegiate
Dictionary, 11th Edition", 2009.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <http://www.rfc-editor.org/info/rfc3550>.
[RFC4475] Sparks, R., Ed., Hawrylyshen, A., Johnston, A., Rosenberg,
J., and H. Schulzrinne, "Session Initiation Protocol (SIP)
Torture Test Messages", RFC 4475, DOI 10.17487/RFC4475,
May 2006, <http://www.rfc-editor.org/info/rfc4475>.
[RFC5137] Klensin, J., "ASCII Escaping of Unicode Characters",
BCP 137, RFC 5137, DOI 10.17487/RFC5137, February 2008,
<http://www.rfc-editor.org/info/rfc5137>.
[RFC6949] Flanagan, H. and N. Brownlee, "RFC Series Format
Requirements and Future Development", RFC 6949,
DOI 10.17487/RFC6949, May 2013,
<http://www.rfc-editor.org/info/rfc6949>.
[RFC7322] Flanagan, H. and S. Ginoza, "RFC Style Guide", RFC 7322,
DOI 10.17487/RFC7322, September 2014,
<http://www.rfc-editor.org/info/rfc7322>.
[RFC7564] Saint-Andre, P. and M. Blanchet, "PRECIS Framework:
Preparation, Enforcement, and Comparison of
Internationalized Strings in Application Protocols",
RFC 7564, DOI 10.17487/RFC7564, May 2015,
<http://www.rfc-editor.org/info/rfc7564>.
[RFC7613] Saint-Andre, P. and A. Melnikov, "Preparation,
Enforcement, and Comparison of Internationalized Strings
Representing Usernames and Passwords", RFC 7613,
DOI 10.17487/RFC7613, August 2015,
<http://www.rfc-editor.org/info/rfc7613>.
[UnicodeCurrent]
The Unicode Consortium, "The Unicode Standard",
2014-present, <http://www.unicode.org/versions/latest/>.
Appendix A. Acknowledgements
With many thanks to the members of the IAB i18n program and the RFC
Format Design Team.
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Author's Address
Heather Flanagan (editor)
RFC Editor
Email: rse@rfc-editor.org
URI: http://orcid.org/0000-0002-2647-2220
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