IMAPEXT A. Melnikov
Internet-Draft Isode Limited
Intended status: Standards Track February 14, 2009
Expires: August 18, 2009
Additional collation algorithms for use in IMAP and Sieve
draft-ietf-morg-collations-00
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Abstract
This document defines extra collation that were found useful when
searching for text in email messages.
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Note
A revised version of this draft document will be submitted to the RFC
editor as a Proposed Standard for the Internet Community. Discussion
and suggestions for improvement are requested, and should be sent to
morg@ietf.org.
Table of Contents
1. Conventions used in this document . . . . . . . . . . . . . . 3
2. ASCII Signed Numeric Collation Description . . . . . . . . . 3
2.1. ASCII Signed Numeric Collation Registration . . . . . . . . . 4
3. ASCII Punctuation Ignore Numeric Collation Description . . . 4
3.1. ASCII Punctuation Ignore Numeric Collation Registration . . . 5
4. Other Collations . . . . . . . . . . . . . . . . . . . . . . 5
5. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . 6
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1. Conventions used in this document
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 RFC 2119 [Kwds].
2. ASCII Signed Numeric Collation Description
The "i;ascii-signed-numeric" collation is a simple collation intended
for use with arbitrarily-sized, signed decimal integer numbers stored
as octet strings. US-ASCII digits (0x30 to 0x39) represent digits of
the numbers. The numbers can have an arbitrary number of leading US-
ASCII whitespace characters (0x20), optionally followed by the sign
("+", "-") and then by digits of the number. If the "+" sign is
omitted, the number is considered to be positive.
Before converting from string to integer, all leading whitespace
characters are removed. If no "+" or "-" character is found, "+" is
then prepended to the string. And finally, the input string is
truncated at the first non-digit character, not counting the "+"/"-"
prefix. All input is valid for this collation; strings that do not
start (after whitespace removal) with a "+", "-" or a digit represent
positive infinity.
The collation supports equality and ordering, but does not support
the substring operation.
The equality operation returns "match" if the two strings represent
the same number (i.e., leading whitespaces, zeroes and trailing non-
digits are disregarded), and "no-match" if the two strings represent
different numbers.
The ordering operation returns "less" if the first string represents
a smaller number than the second, "equal" if they represent the same
number, and "greater" if the first string represents a larger number
than the second.
Some examples: " -500" is less than "-90", " 0" is less than "1M",
and "1" is less than "4294967298". "4294967298", "04294967298", and
"4294967298b" are all equal. "04294967298" is less than "". "+", "-",
"", "x", and "y" are equal.
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2.1. ASCII Signed Numeric Collation Registration
<?xml version='1.0'?>
<!DOCTYPE collation SYSTEM 'collationreg.dtd'>
<collation rfc="XXXX" scope="other" intendedUse="common">
<identifier>i;ascii-signed-numeric</identifier>
<title>ASCII Signed Numeric</title>
<operations>equality order</operations>
<specification>RFC XXXX</specification>
<owner>IETF</owner>
<submitter>alexey.melnikov@isode.com</submitter>
</collation>
3. ASCII Punctuation Ignore Numeric Collation Description
The "i;ascii-punc-ignore-numeric" collation is a collation intended
for use with arbitrarily-sized, unsigned decimal integer numbers
stored as octet strings. US-ASCII digits (0x30 to 0x39) represent
digits of the numbers. Any digit of such numbers can be followed or
preceeded by any number of the following US-ASCII characters, which
are ignored for the purpose of comparison: " " (0x20), "-", "+", ",",
";", ".". [[anchor5: The list of characters to ignore is to be
discussed.]]
Before converting from string to integer, all characters to be
ignored are removed from the string. After that, the input string is
truncated at the first non-digit character. All input is valid for
this collation; strings that do not start (after removal of all
characters to ignore) with a digit represent positive infinity.
The collation supports equality and ordering, but does not support
the substring operation.
The equality operation returns "match" if the two strings represent
the same number (i.e., leading whitespaces, zeroes and trailing non-
digits are disregarded), and "no-match" if the two strings represent
different numbers.
The ordering operation returns "less" if the first string represents
a smaller number than the second, "equal" if they represent the same
number, and "greater" if the first string represents a larger number
than the second.
Some examples: "+1-500" is less than "2 50.0", " 0" is less than
"1M", and "1" is less than "4294967298". "4294967298", "04294967298",
and "4294967298b" are all equal. "04294967298" is less than "". "+",
"-", "", "x", and "y" are equal.
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3.1. ASCII Punctuation Ignore Numeric Collation Registration
<?xml version='1.0'?>
<!DOCTYPE collation SYSTEM 'collationreg.dtd'>
<collation rfc="XXXX" scope="other" intendedUse="common">
<identifier>i;ascii-punc-ignore-numeric</identifier>
<title>ASCII Punctuation Ignore Numeric</title>
<operations>equality order</operations>
<specification>RFC XXXX</specification>
<owner>IETF</owner>
<submitter>alexey.melnikov@isode.com</submitter>
</collation>
4. Other Collations
[[anchor8: Other collations to consider: case preserving version of
i;unicode-casemap defined in RFC 5051.]]
5. Formal Syntax
The following syntax specification uses the augmented Backus-Naur
Form (BNF) as described in [ABNF]. Terms not defined here are taken
from [ABNF].
ascii-signed-numeric = *SP [("-" / "+")] 1*DIGIT
; This production defines valid string prefixes
punc-ignore-unsigned-numeric = *punctuation DIGIT
*(punctuation / DIGIT)
; This production defines valid string prefixes
punctuation = SP / "+" / "-" / "." / "," / ";"
6. Security Considerations
[[anchor9: TBD.]]
7. IANA Considerations
TBD.
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8. Acknowledgements
TBD.
9. References
9.1. Normative References
[ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 5234, January 2008.
[Kwds] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
[RFC4790] Newman, C., Duerst, M., and A. Gulbrandsen, "Internet
Application Protocol Collation Registry", RFC 4790,
March 2007.
9.2. Informative References
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
4rev1", RFC 3501, March 2003.
Author's Address
Alexey Melnikov
Isode Limited
5 Castle Business Village
36 Station Road
Hampton, Middlesex TW12 2BX
UK
Email: Alexey.Melnikov@isode.com
URI: http://www.melnikov.ca/
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