- From: Francois Yergeau <FYergeau@alis.com>
- Date: Thu, 19 Sep 2002 09:49:21 -0400
- To: Patrik Fältström <paf@cisco.com>
- Cc: ietf-charsets@iana.org, Bert Wijnen <bwijnen@lucent.com>
Patrik Fältström wrote:
> It's the semi-weekly IESG teleconf today again, and as usual I would
> like to report the status of this document -- as IESG find it being
> extremely important, if not necessary, for development of other
> standards which have normative references to it.
>
> How is it going? I have not seen anything else than
> draft-yergeau-rfc2279bis?
I hope it's not too late for the teleconf. I have been overcommitted and
still wanted to double-check a couple of things, but here is what I have
now. I think I have covered most outstanding comments, with the notable
exception of the BOM issue raised by Martin Dürst. This one is neither
trivial nor uncontroversial, and I have not seen anything ressembling a
consensus, so it remains open (no changes to the draft). On other issues, I
think the Changes section pretty accurately reflects the changes made.
The draft has been sent to the I-D editor and is attached hereunder.
Regards,
--
François
----------------------------8<-------------------------
Network Working Group F. Yergeau
Internet-Draft Alis Technologies
Expires: March 2, 2003 September 1, 2002
UTF-8, a transformation format of ISO 10646
draft-yergeau-rfc2279bis-01
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 March 2, 2003.
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
<1>
ISO/IEC 10646-1 defines a large character set called the Universal
Character Set (UCS) which encompasses most of the world's writing
systems. The originally proposed encodings of the UCS, however, were
not compatible with many current applications and protocols, and this
has led to the development of UTF-8, the object of this memo. UTF-8
has the characteristic of preserving the full US-ASCII range,
providing compatibility with file systems, parsers and other software
that rely on US-ASCII values but are transparent to other values.
This memo updates and replaces RFC 2279.
<2>
Discussion of this draft should take place on the ietf-
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charsets@iana.org mailing list.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational conventions . . . . . . . . . . . . . . . . . . . . 5
3. UTF-8 definition . . . . . . . . . . . . . . . . . . . . . . . 6
4. Syntax of UTF-8 Byte Sequences . . . . . . . . . . . . . . . . 8
5. Versions of the standards . . . . . . . . . . . . . . . . . . 9
6. Byte order mark (BOM) . . . . . . . . . . . . . . . . . . . . 10
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8. MIME registration . . . . . . . . . . . . . . . . . . . . . . 13
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
10. Security Considerations . . . . . . . . . . . . . . . . . . . 15
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . 16
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 17
A. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18
B. Changes from RFC 2279 . . . . . . . . . . . . . . . . . . . . 19
Full Copyright Statement . . . . . . . . . . . . . . . . . . . 20
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1. Introduction
<3>
ISO/IEC 10646 [ISO.10646-1] defines a large character set called the
Universal Character Set (UCS), which encompasses most of the world's
writing systems. The same set of characters is defined by the
Unicode standard [UNICODE], which further defines additional
character properties and other application details of great interest
to implementors. Up to the present time, changes in Unicode and
amendments and additions to ISO/IEC 10646 have tracked each other, so
that the character repertoires and code point assignments have
remained in sync. The relevant standardization committees have
committed to maintain this very useful synchronism.
<4>
ISO/IEC 10646 and Unicode define several encoding forms of their
common repertoire: UTF-8, UCS-2, UTF-16, UCS-4 and UTF-32. In an
encoding form, each character is represented as one or more encoding
units. All standard UCS encoding forms except UTF-8 have an encoding
unit larger than one octet, making them hard to use in many current
applications and protocols that assume 8 or even 7 bit characters.
<5>
UTF-8, the object of this memo, has a one-octet encoding unit. It
uses all bits of an octet, but has the quality of preserving the full
US-ASCII [US-ASCII] range: US-ASCII characters are encoded in one
octet having the normal US-ASCII value, and any octet with such a
value can only stand for an US-ASCII character, and nothing else.
<6>
UTF-8 encodes UCS characters as a varying number of octets, where the
number of octets, and the value of each, depend on the integer value
assigned to the character in ISO/IEC 10646 (the character number,
a.k.a. code point or Unicode scalar value). This encoding form has
the following characteristics (all values are in hexadecimal):
<7>
o Character numbers from U+0000 to U+007F (US-ASCII repertoire)
correspond to octets 00 to 7F (7 bit US-ASCII values). A direct
consequence is that a plain ASCII string is also a valid UTF-8
string.
<8>
o US-ASCII octet values do not appear otherwise in a UTF-8 encoded
character stream. This provides compatibility with file systems
or other software (e.g. the printf() function in C libraries)
that parse based on US-ASCII values but are transparent to other
values.
<9>
o Round-trip conversion is easy between UTF-8 and other encoding
forms.
<10>
o The first octet of a multi-octet sequence indicates the number of
octets in the sequence.
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<11>
o The octet values C0, C1, FE and FF never appear. If the range of
character numbers is restricted to U+0000..U+10FFFF (the UTF-16
accessible range), then the octet values F5..FD also never appear.
<12>
o Character boundaries are easily found from anywhere in an octet
stream.
<13>
o The lexicographic sorting order of UTF-8 strings is the same as if
ordered by character numbers. Of course this is of limited
interest since a sort order based on character numbers is not
culturally valid.
<14>
o The Boyer-Moore fast search algorithm can be used with UTF-8 data.
<15>
o UTF-8 strings can be fairly reliably recognized as such by a
simple algorithm, i.e. the probability that a string of
characters in any other encoding appears as valid UTF-8 is low,
diminishing with increasing string length.
<16>
UTF-8 was originally a project of the X/Open Joint
Internationalization Group XOJIG with the objective to specify a File
System Safe UCS Transformation Format [FSS_UTF] that is compatible
with UNIX systems, supporting multilingual text in a single encoding.
The original authors were Gary Miller, Greger Leijonhufvud and John
Entenmann. Later, Ken Thompson and Rob Pike did significant work for
the formal definition of UTF-8.
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2. Notational conventions
<17>
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].
<18>
UCS characters are designated by the U+HHHH notation, where HHHH is a
string of from 4 to 6 hexadecimal digits representing the character
number in ISO/IEC 10646.
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3. UTF-8 definition
<19>
UTF-8 is defined by Annex D of ISO/IEC 10646-1 [ISO.10646-1].
Descriptions and formulae can also be found in the Unicode Standard
[UNICODE] and in [FSS_UTF].
<20>
In UTF-8, characters are encoded using sequences of 1 to 6 octets.
If the range of character numbers is restricted to U+0000..U+10FFFF
(the UTF-16 accessible range), then only sequences of one to four
octets will occur. The only octet of a "sequence" of one has the
higher-order bit set to 0, the remaining 7 bits being used to encode
the character number. In a sequence of n octets, n>1, the initial
octet has the n higher-order bits set to 1, followed by a bit set to
0. The remaining bit(s) of that octet contain bits from the number
of the character to be encoded. The following octet(s) all have the
higher-order bit set to 1 and the following bit set to 0, leaving 6
bits in each to contain bits from the character to be encoded.
<21>
The table below summarizes the format of these different octet types.
The letter x indicates bits available for encoding bits of the
character number.
Char. number range | UTF-8 octet sequence
(hexadecimal) | (binary)
--------------------+---------------------------------------------
0000 0000-0000 007F | 0xxxxxxx
0000 0080-0000 07FF | 110xxxxx 10xxxxxx
0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
0001 0000-001F FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
0020 0000-03FF FFFF | 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
0400 0000-7FFF FFFF | 1111110x 10xxxxxx ... 10xxxxxx
<22>
Encoding a character to UTF-8 proceeds as follows:
<23>
1. Determine the number of octets required from the character number
and the first column of the table above. It is important to note
that the rows of the table are mutually exclusive, i.e. there is
only one valid way to encode a given character.
<24>
2. Prepare the high-order bits of the octets as per the second
column of the table.
<25>
3. Fill in the bits marked x from the bits of the character number,
expressed in binary. Start from the lower-order bits of the
character number and put them first in the last octet of the
sequence, then the next to last, etc. until all x bits are
filled in.
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<26>
The definition of UTF-8 prohibits encoding character numbers between
U+D800 and U+DFFF, which are reserved for use with the UTF-16
encoding form (as surrogate pairs) and do not directly represent
characters. When encoding in UTF-8 from UTF-16 data, it is necessary
to first decode the UTF-16 data to obtain character numbers, which
are then encoded in UTF-8 as described above.
<27>
Decoding a UTF-8 character proceeds as follows:
<28>
1. Initialize a binary number with all bits set to 0. Up to 31 bits
may be needed (up to 21 if the range of character numbers is
known to be restricted to the UTF-16 accessible range).
<29>
2. Determine which bits encode the character number from the number
of octets in the sequence and the second column of the table
above (the bits marked x).
<30>
3. Distribute the bits from the sequence to the binary number, first
the lower-order bits from the last octet of the sequence and
proceeding to the left until no x bits are left. The binary
number is now equal to the character number.
<31>
Implementations of the decoding algorithm above MUST protect against
decoding invalid sequences. For instance, a naive implementation may
decode the overlong UTF-8 sequence C0 80 into the character U+0000,
or the surrogate pair ED A1 8C ED BE B4 into U+233B4. Decoding
invalid sequences may have security consequences or cause other
problems. See Security Considerations (Section 10) below.
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4. Syntax of UTF-8 Byte Sequences
<32>
A UTF-8 string is a sequence of bytes representing a sequence of UCS
characters. The byte sequence is valid UTF-8 only if it matches the
following syntax, which is derived from the rules for encoding UTF-8
and is expressed in the ABNF of [RFC2234].
UTF8-string = *( UTF8-char )
UTF8-char = UTF8-1 /
UTF8-2-head 1( UTF8-tail ) /
UTF8-3-head 1( UTF8-tail ) /
UTF8-4-head 2( UTF8-tail ) /
UTF8-5-head 3( UTF8-tail ) /
UTF8-6-head 4( UTF8-tail )
UTF8-1 = %x00-7F
UTF8-2-head = %xC2-DF
UTF8-3-head = %xE0 %xA0-BF / %xE1-EC %x80-BF /
%xED %x80-9F / %xEE-EF %x80-BF
UTF8-4-head = %xF0 %x90-BF / %xF1-F7 %x80-BF
UTF8-5-head = %xF8 %x88-BF / %xF9-FB %x80-BF
UTF8-6-head = %xFC %x84-BF / %xFD %x80-BF
UTF8-tail = %x80-BF
UTF8-string = *( UTF8-char )
UTF8-char = UTF8-1 / UTF8-2 / UTF8-3 / UTF8-4 / UTF8-5 / UTF8-6
UTF8-char = UTF8-1 /
UTF8-2 /
UTF8-3 /
UTF8-4 /
UTF8-5 /
UTF8-6
UTF8-1 = %x00-7F
UTF8-2 = %xC2-DF UTF8-tail
UTF8-3 = %xE0 %xA0-BF UTF8-tail / %xE1-EC 2( UTF8-tail ) /
%xED %x80-9F UTF8-tail / %xEE-EF 2( UTF8-tail )
UTF8-4 = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F7 3( UTF8-tail )
UTF8-5 = %xF8 %x88-BF 3( UTF8-tail ) / %xF9-FB 4( UTF8-tail )
UTF8-6 = %xFC %x84-BF 4( UTF8-tail ) / %xFD 5( UTF8-tail )
UTF8-tail = %x80-BF
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5. Versions of the standards
<33>
ISO/IEC 10646 is updated from time to time by publication of
amendments and additional parts; similarly, new versions of the
Unicode standard are published over time. Each new version obsoletes
and replaces the previous one, but implementations, and more
significantly data, are not updated instantly.
<34>
In general, the changes amount to adding new characters, which does
not pose particular problems with old data. In 1996, Amendment 5 to
the 1993 edition of ISO/IEC 10646 and Unicode 2.0 moved and expanded
the Korean Hangul block, thereby making any previous data containing
Hangul characters invalid under the new version. Unicode 2.0 has the
same difference from Unicode 1.1. The justification for allowing
such an incompatible change was that there were no major
implementations and no significant amounts of data containing Hangul.
The incident has been dubbed the "Korean mess", and the relevant
committees have pledged to never, ever again make such an
incompatible change (see Unicode Consortium Policies [1]).
<35>
New versions, and in particular any incompatible changes, have
consequences regarding MIME charset labels, to be discussed in MIME
registration (Section 8).
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6. Byte order mark (BOM)
<36>
The Unicode Standard and ISO 10646 define the character "ZERO WIDTH
NO-BREAK SPACE" (U+FEFF), which is also known informally as "BYTE
ORDER MARK" (abbreviated "BOM"). The latter name hints at a second
possible usage of the character, in addition to its normal use as a
genuine "ZERO WIDTH NO-BREAK SPACE" within text. This usage,
suggested by Unicode section 2.7 and ISO/IEC 10646 Annex H
(informative), is to prepend a U+FEFF character to a stream of UCS
characters as a "signature"; a receiver of such a serialized stream
may then use the initial character as a hint that the stream consists
of UCS characters. The signature can also be used to recognize which
UCS encoding is involved and, with encodings having a multi-octet
encoding unit, as a way to recognize the serialization order of the
octets. UTF-8 having a single-octet encoding unit, this last
function is useless and the BOM will always appear as the octet
sequence EF BB BF.
<37>
It is important to understand that the character U+FEFF appearing at
any position other than the beginning of a stream MUST be interpreted
with the semantics for the zero-width non-breaking space, and MUST
NOT be interpreted as a byte-order mark. The contrapositive of that
statement is not always true: the character U+FEFF in the first
position of a stream MAY be interpreted as a zero-width non-breaking
space, and is not always a byte-order mark. For example, if a
process splits a UCS string into many parts, a part might begin with
U+FEFF because there was a zero-width no-break space at the beginning
of that substring.
<38>
The Unicode standard further suggests than an initial U+FEFF
character may be stripped before processing the text, the rationale
being that such a character in initial position may be an artifact of
the encoding (an encoding signature), not a genuine intended "ZERO
WIDTH NO-BREAK SPACE". Note that such stripping might affect an
external process at a different layer (such as a digital signature or
a count of the characters) that is relying on the presence of all
characters in the stream.
<39>
In particular, in UTF-8 plain text it is likely, but not certain,
that an initial octet sequence of EF BB BF is a signature. When
concatenating two strings, it is important to strip out those
signatures, because otherwise the resulting string may contain an
unintended "ZERO WIDTH NO-BREAK SPACE" at the connection point.
<40>
In an attempt at diminishing the uncertainty, Unicode 3.2 adds a new
character, U+2060 WORD JOINER, with exactly the same semantics and
usage as U+FEFF except for the signature function, and strongly
recommends its exclusive use for expressing word-joining semantics.
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Eventually, following this recommendation will make it all but
certain that any initial U+FEFF is a signature, not an intended "ZERO
WIDTH NO-BREAK SPACE".
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7. Examples
<41>
The character sequence U+0041 U+2262 U+0391 U+002E "A<NOT IDENTICAL
TO><ALPHA>." is encoded in UTF-8 as follows:
--+--------+-----+--
41 E2 89 A2 CE 91 2E
--+--------+-----+--
<42>
The character sequence U+D55C U+AD6D U+C5B4 (Korean "hangugeo",
meaning "the Korean language") is encoded in UTF-8 as follows:
--------+--------+--------
ED 95 9C EA B5 AD EC 96 B4
--------+--------+--------
<43>
The character sequence U+65E5 U+672C U+8A9E (Japanese "nihongo",
meaning "the Japanese language") is encoded in UTF-8 as follows:
--------+--------+--------
E6 97 A5 E6 9C AC E8 AA 9E
--------+--------+--------
<44>
The character U+233B4 (a Chinese character meaning 'stump of tree'),
prepended with a UTF-8 BOM, is encoded in UTF-8 as follows:
--------+-----------
EF BB BF F0 A3 8E B4
--------+-----------
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8. MIME registration
<45>
This memo serves as the basis for registration of the MIME charset
parameter for UTF-8, according to [RFC2978]. The charset parameter
value is "UTF-8". This string labels media types containing text
consisting of characters from the repertoire of ISO/IEC 10646
including all amendments at least up to amendment 5 of the 1993
edition (Korean block), encoded to a sequence of octets using the
encoding scheme outlined above. UTF-8 is suitable for use in MIME
content types under the "text" top-level type.
<46>
It is noteworthy that the label "UTF-8" does not contain a version
identification, referring generically to ISO/IEC 10646. This is
intentional, the rationale being as follows:
<47>
A MIME charset label is designed to give just the information needed
to interpret a sequence of bytes received on the wire into a sequence
of characters, nothing more (see [RFC2045], section 2.2). As long as
a character set standard does not change incompatibly, version
numbers serve no purpose, because one gains nothing by learning from
the tag that newly assigned characters may be received that one
doesn't know about. The tag itself doesn't teach anything about the
new characters, which are going to be received anyway.
<48>
Hence, as long as the standards evolve compatibly, the apparent
advantage of having labels that identify the versions is only that,
apparent. But there is a disadvantage to such version-dependent
labels: when an older application receives data accompanied by a
newer, unknown label, it may fail to recognize the label and be
completely unable to deal with the data, whereas a generic, known
label would have triggered mostly correct processing of the data,
which may well not contain any new characters.
<49>
Now the "Korean mess" (ISO/IEC 10646 amendment 5) is an incompatible
change, in principle contradicting the appropriateness of a version
independent MIME charset label as described above. But the
compatibility problem can only appear with data containing Korean
Hangul characters encoded according to Unicode 1.1 (or equivalently
ISO/IEC 10646 before amendment 5), and there is arguably no such data
to worry about, this being the very reason the incompatible change
was deemed acceptable.
<50>
In practice, then, a version-independent label is warranted, provided
the label is understood to refer to all versions after Amendment 5,
and provided no incompatible change actually occurs. Should
incompatible changes occur in a later version of ISO/IEC 10646, the
MIME charset label defined here will stay aligned with the previous
version until and unless the IETF specifically decides otherwise.
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9. IANA Considerations
<51>
The entry for UTF-8 in the IANA charset registry should be updated to
point to this memo.
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10. Security Considerations
<52>
Implementors of UTF-8 need to consider the security aspects of how
they handle illegal UTF-8 sequences. It is conceivable that in some
circumstances an attacker would be able to exploit an incautious UTF-
8 parser by sending it an octet sequence that is not permitted by the
UTF-8 syntax.
<53>
A particularly subtle form of this attack can be carried out against
a parser which performs security-critical validity checks against the
UTF-8 encoded form of its input, but interprets certain illegal octet
sequences as characters. For example, a parser might prohibit the
NUL character when encoded as the single-octet sequence 00, but
erroneously allow the illegal two-octet sequence C0 80 and interpret
it as a NUL character. Another example might be a parser which
prohibits the octet sequence 2F 2E 2E 2F ("/../"), yet permits the
illegal octet sequence 2F C0 AE 2E 2F. This last exploit has
actually been used in a widespread virus attacking Web servers in
2001; the security threat is thus very real.
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Bibliography
[FSS_UTF] X/Open Company Ltd., "X/Open CAE Specification C501 --
File System Safe UCS Transformation Format (FSS_UTF)",
ISBN 1-85912-082-2, April 1995.
[ISO.10646-1] International Organization for Standardization,
"Information Technology - Universal Multiple-octet
coded Character Set (UCS) - Part 1: Architecture and
Basic Multilingual Plane", ISO Standard 10646-1, 2000.
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet
Mail Extensions (MIME) Part One: Format of Internet
Message Bodies", RFC 2045, November 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[RFC2978] Freed, N. and J. Postel, "IANA Charset Registration
Procedures", BCP 19, RFC 2978, October 2000.
[UNICODE] The Unicode Consortium, "The Unicode Standard --
Version 3.2", defined by The Unicode Standard,
Version 3.0 (Reading, MA, Addison-Wesley, 2000. ISBN
0-201-61633-5), as amended by the Unicode Standard
Annex #27: Unicode 3.1 (see http://www.unicode.org/
reports/tr27) and by the Unicode Standard Annex #28:
Unicode 3.2 (see http://www.unicode.org/reports/tr28),
March 2002, <http://www.unicode.org/unicode/standard/
versions/enumeratedversions.html#Unicode_3_2_0>.
[US-ASCII] American National Standards Institute, "Coded
Character Set - 7-bit American Standard Code for
Information Interchange", ANSI X3.4, 1986.
[1] <http://www.unicode.org/unicode/standard/policies.html>
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Author's Address
François Yergeau
Alis Technologies
100, boul. Alexis-Nihon, bureau 600
Montréal, QC H4M 2P2
Canada
Phone: +1 514 747 2547
Fax: +1 514 747 2561
EMail: fyergeau@alis.com
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Appendix A. Acknowledgements
<62>
The following have participated in the drafting and discussion of
this memo: James E. Agenbroad, Harald Alvestrand, Andries Brouwer,
Mark Davis, Martin J. Dürst, Patrick Fältström, Ned Freed, David
Goldsmith, Tony Hansen, Edwin F. Hart, Paul Hoffman, David Hopwood,
Kent Karlsson, Markus Kuhn, Michael Kung, Alain LaBonté, John
Gardiner Myers, Dan Oscarsson, Murray Sargent, Markus Scherer, Keld
Simonsen, Arnold Winkler, Kenneth Whistler and Misha Wolf.
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Appendix B. Changes from RFC 2279
<63>
<64>
o Significantly shortened Introduction. No more mention of UTF-1 or
UTF-7, of Transformation Formats.
<65>
o Straightened out terminology. UTF-8 now described in terms of an
encoding form of the character number. UCS-2 and UCS-4 almost
disappeared.
<66>
o Note warning against decoding of invalid sequences turned into a
normative MUST NOT.
<67>
o New section about the BOM, mostly extracted and slightly adapted
from RFC 2781.
<68>
o Updated a couple of references (10646-1:2000, Unicode 3.2, RFC
2978).
<69>
o Added TOC.
<70>
o Removed suggested UNICODE-1-1-UTF-8 MIME charset registration.
<71>
o New "Notational conventions" section about RFC 2119 and U+HHHH
notation.
<72>
o Pointer to Unicode Consortium Policies added in "Versions of the
standards" section.
<73>
o Added a fourth example with a non-BMP character and a BOM.
<74>
o Added a paragraph about U+2060 WORD JOINER.
<75>
o Enumerate more byte values impossible in UTF-8, either as a result
of forbidding overlong sequences or of restricting to the UTF-16
accessible range.
<76>
o Added "IANA Considerations" section to ask that the UTF-8 entry in
the charset registry point to this memo.
Yergeau Expires March 2, 2003 [Page 19]
Internet-Draft UTF-8 September 2002
Full Copyright Statement
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
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Yergeau Expires March 2, 2003 [Page 20]
Received on Thursday, 19 September 2002 09:51:44 UTC