One document matched: draft-ietf-precis-mappings-01.xml
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<?rfc toc="yes"?>
<rfc category="info" docName="draft-ietf-precis-mappings-01" ipr="trust200902">
<front>
<title abbrev="precis mapping">Mapping characters for precis classes</title>
<author fullname="Yoshiro YONEYA" initials="Y" surname="YONEYA">
<organization>JPRS</organization>
<address>
<postal>
<street>Chiyoda First Bldg. East 13F</street>
<street>3-8-1 Nishi-Kanda</street>
<city>Chiyoda-ku</city>
<region>Tokyo</region>
<code>101-0065</code>
<country>Japan</country>
</postal>
<phone>+81 3 5215 8451</phone>
<email>yoshiro.yoneya@jprs.co.jp</email>
</address>
</author>
<author fullname="Takahiro NEMOTO" initials="T" surname="NEMOTO">
<organization>Keio University</organization>
<address>
<postal>
<street>Graduate School of Media Design</street>
<street>4-1-1 Hiyoshi, Kohoku-ku</street>
<city>Yokohama</city>
<region>Kanagawa</region>
<code>223-8526</code>
<country>Japan</country>
</postal>
<phone>+81 45 564 2517</phone>
<email>t.nemo10@kmd.keio.ac.jp</email>
</address>
</author>
<date day="26" month="December" year="2012"/>
<abstract>
<t>
Preparation and comparison of internationalized strings ("precis")
framework <xref target="I-D.ietf-precis-framework"/> is defining
several classes of strings for preparation and comparison. In the
document, case mapping is defined because many of protocols handle
case sensitive or case insensitive string comparison and therefore
preparation of string is mandatory. As described in IDNA mapping
<xref target="RFC5895"/> and precis problem statement
<xref target="I-D.ietf-precis-problem-statement"/>, mappings in
internationalized strings are not limited to case, but also width,
delimiters and/or other specials are taken into consideration.
This document is a guideline for authors of protocol profiles of precis framework
and describes the mappings, that may be performed before precis framework,
that must be considered between receiving user input and passing
permitted code points to internationalized protocols.
</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>
In many cases, user input of internationalized strings is generated
by input method editor ("IME") or copy-and-paste from free text.
Usually users do not care case and/or width of input characters
because they are identical for users' eyes. Further, users rarely
switch IME state to input special characters such as protocol
elements. For Internationalized Domain Names ("IDNs"), IDNA Mapping
<xref target="RFC5895"/> describes methods to treat these issues.
For precis strings, case mapping is defined as a process in precis
framework <xref target="I-D.ietf-precis-framework"/>, but width
mapping, delimiter mapping, special mapping and language dependent mapping are not defined.
Handling of mappings other than case is also important to increase chance of
strings match as users expect.
This document is a guideline for authors of protocol profiles of precis framework
and describes the mappings that must be considered
between receiving user input and passing permitted code points to
internationalized protocols.
Mappings that this document describes are expected to perform before precis framework as well as Mapping Characters for IDNA2008
<xref target="RFC5895"/>.
</t>
</section>
<!-- ******************************************************************************* -->
<section title="Types of mapping" anchor="type">
<t>
This document defines two types of mapping. One is protocol independent mapping
that doesn't depend on protocol rules and the other is protocol dependent mapping that depend on protocol rules.
This document defines some mappings in these mapping types.
Authors of protocol profiles of precis framework should need to give careful consideration to choice of mappings.
</t>
<t>
Each mapping type is described in following sections.
</t>
</section>
<!-- ******************************************************************************* -->
<section title="Protocol independent mapping" anchor="pim">
<t>
Protocol independent mapping is a mapping that doesn't depend on protocol rules.
</t>
<section title="Width mapping">
<t>
Fullwidth and halfwidth characters (those defined with
Decomposition Types <wide> and <narrow>) are mapped to
their decomposition mappings as shown in the Unicode character
database <xref target="Unicode"/>.
</t>
<t>
Width mapping will increase backward compatibility with Stringprep
<xref target="RFC3454"/> and precis framework
<xref target="I-D.ietf-precis-framework"/>. Because in a
Stringprep profile which specifies Unicode normalization form KC
(NFKC) for normalization method, fullwidth/halfwidth characters
are mapped into its compatible form. If a precis framework
profile specified NFKC (which is not recommended), width mapping
might not be useful.
</t>
</section>
</section>
<!-- ******************************************************************************* -->
<section title="Protocol dependent mapping" anchor="pdm">
<t>
Protocol dependent mapping is a mapping that depend on protocol rules.
</t>
<section title="Delimiter mapping">
<t>
Definitions of delimiters in certain protocols are differ from
each other. Therefore, delimiter mapping table should be based on
well defined mapping table for each protocol.
</t>
<t>
One of the most useful case of delimiter mapping is when FULL STOP
character (U+002E) is a delimiter as well as domain name. Some of
IME generates FULL STOP compatible characters such as IDEOGRAPHIC
FULL STOP (U+3002) when users type FULL STOP on the keyboard.
</t>
</section>
<section title="Special mapping" anchor="spm">
<t>
Certain protocols have characters which need to map different character from
precis framework defined mapping rule other than delimiter characters.
In this document, these mappings are named special mapping. They are differ from each protocol.
Therefore, special mapping table should be based on well defined mapping table for each protocol.
Examples of special mapping are following;
<list style='symbols'>
<t>White spaces are mapped to SPACE (U+0020)</t>
<t>Some characters such as control characters are mapped to nothing (Deletion)</t>
</list>
LDAPprep<xref target="RFC4518"/> defines the rule that some codepoints(<xref target="cplist4518"/>) are mapped to SPACE (U+0020).
</t>
</section>
<section title="Local case mapping" anchor="lcm">
<t>
Local case mapping is case folding that depend on language context.
For example, given there is upper case I in a user ID strings, you
should care what's language context that this user ID depend on when
this character is mapped into lower case character. And if this
depends on Turkish, the character should be mapped into LATIN SMALL
LETTER DOTLESS I (U+0131) as this character's lower case.
</t>
<t>
This document defines characters that need local case mapping based on
the Specialcasing.txt <xref target="Specialcasing"/> in section 3.13
of The Unicode Standerd <xref target="Unicode"/> to solve such a problem for precis framework.
Local case mapping targets only characters that get two different results to perfom just casefolding
that is defined in the Casefolding.txt <xref target="Casefolding"/> and perfom special casefolding
that is defined in the Specialcasing.txt then casefolding, because precis framework have casefolding.
</t>
<t>
There are two types casefoldings defined as Unconditional Mappings and Conditional Mappings in the Specialcasing.txt.
Conditional mappings have Language-Insensitive Mappings that targets characters whose full case mappings do not depend on language, but do
depend on context and Language-Sensitive Mappings that these are characters whose full case mappings depend on language and perhaps also
context.
</t>
<t>
Of these mappings, characters that Unconditional Mappings and Language-Insensitive Mappings in Conditional Mappings target are mapped into
same codepoint(s) with just casefolding and special casefolding then casefolding.
But characters that Language-Sensitive Mappings in Conditional Mappings targets are mapped into different codepoint with them.
Therefore this document defined characters that are a part of characters of Lithuanian(lt), Turkish(tr) and Azerbaijanian(az) that Language-Sensitive Mappings targets
as targets for local case mapping.
</t>
<t>
Followings are the method to calculate codepoints that local case mapping targets.
Here Casefolding() means casefolding described in the Casefolding.txt <xref target="Casefolding"/>
and Specialcasing() means specialcasing described in the Specialcasing.txt <xref target="Specialcasing"/>.
</t>
<t>
If Casefolding(Specialcasing(cp)) != Casefolding(cp)<vspace/>
Then cp is a target<vspace/>
Else cp is not a target;<vspace/>
</t>
<t>
<xref target="LCM-list"/> "Code points list for local case mapping" lists codepoints are calculated by this method.
</t>
</section>
</section>
<!-- ******************************************************************************* -->
<section title="Applying order of mapping" anchor="aom">
<t>
Basically, applying order of mapping that this document describes aren't sensitive.
This section defines applying order of mapping to minimize effect of codepoint change by mappings.
This mapping order is very general and was designed to be acceptable to the widest user community.
<list style='numbers'>
<t>Width mapping</t>
<t>Delimiter mapping</t>
<t>Special mapping</t>
<t>Local case mapping</t>
<!--t>precis framework</t-->
</list>
Mappings that this document describes are expected to perform before precis framework.
</t>
</section>
<!-- ******************************************************************************* -->
<section title="Open issues" anchor="oi">
<t>
Followings are cullent open issues for this document.
<list style='numbers'>
<t>
Whether is local case mapping belong in additional mappings in precis framework?
</t>
<t>
If local case mapping belong in precis framework, it's necessary to specify mapping order as local case mapping then case mapping.
Because it makes no sense to perform local case mapping after case mapping.
</t>
<t>
Handling order of precis framework and precis mappings is ambiguous. It's necessary to define the order in precis framework or in this document or in both documents.
</t>
</list>
</t>
</section>
<section title="IANA Considerations" anchor="iana">
<t>
This document does not define any IANA-related things.
</t>
</section>
<section title="Security Considerations" anchor="sec">
<t>
As well as Mapping Characters for IDNA2008 <xref target="RFC5895"/>, this document suggests creating mappings that might cause confusion for some users while alleviating confusion in other users.
Such confusion is not covered in any depth in this document.
</t>
</section>
<section title="Acknowledgment" anchor="ack">
<t>
Martin Dürst suggested a need for the case folding about the mapping(map final sigma to sigma, German sz to ss,.).
</t>
<t>
Joe Hildebrand, John Klensin, Marc Blanchet, Pete Resnick and Peter Saint-Andre, et al. gave important suggestion for this document during at WG meeting.
</t>
</section>
</middle>
<back>
<references title="References">
&rfc3454;
&rfc3490;
&rfc3491;
&rfc3722;
&rfc3748;
&rfc4013;
&rfc4314;
&rfc4518;
&rfc5895;
&rfc6120;
&I-D.ietf-precis-framework;
&I-D.ietf-precis-problem-statement;
<reference anchor="Unicode">
<front>
<title>The Unicode Standard, Version 6.2.0</title>
<author initials="" surname="The Unicode Consortium" fullname="">
<organization/>
</author>
<date year="2012"/>
</front>
<seriesInfo name="" value="<http://www.unicode.org/versions/Unicode6.2.0/>"/>
</reference>
<reference anchor="Casefolding">
<front>
<title>CaseFolding-6.2.0.txt</title>
<author initials="" surname="" fullname="">
<organization/>
</author>
<date year=""/>
</front>
<seriesInfo name="Unicode Character Database, July 2011," value="<http://www.unicode.org/Public/6.2.0/ucd/CaseFolding.txt>"/>
</reference>
<reference anchor="Specialcasing">
<front>
<title>SpecialCasing-6.2.0.txt</title>
<author initials="" surname="" fullname="">
<organization/>
</author>
<date year=""/>
</front>
<seriesInfo name="Unicode Character Database, July 2011," value="<http://www.unicode.org/Public/6.2.0/ucd/SpecialCasing.txt>"/>
</reference>
<reference anchor="ISO.3166-1">
<front>
<title>Codes for the representation of names of countries and their subdivisions - Part 1: Country codes</title>
<author>
<organization>International Organization for Standardization</organization>
</author>
<date year="1997" />
</front>
<seriesInfo name="ISO Standard 3166-" value="1:1997"/>
</reference>
</references>
<section title="Mapping type list each protocol" anchor="maplist">
<section title="Mapping type list for each protocol" anchor="maptype">
<t>
This table is the mapping type list for each protocol.
Values marked "o" indicate that the protocol use the type of mapping.
Values marked "-" indicate that the protocol doesn't use the type of mapping.
</t>
<figure>
<artwork><![CDATA[
+----------------------+-------------+-----------+------+---------+
| \ Type of mapping | Width | Delimiter | Case | Special |
| RFC \ | (NFKC) | | | |
+----------------------+-------------+-----------+------+---------+
| 3490 | - | o | - | - |
| 3491 | o | - | o | - |
| 3722 | o | - | o | - |
| 3748 | o | - | - | o |
| 4013 | o | - | - | o |
| 4314 | o | - | - | o |
| 4518 | o | - | o | o |
| 6120 | - | - | o | - |
+----------------------+-------------+-----------+------+---------+
]]></artwork>
</figure>
</section>
</section>
<section title="Codepoints which need special mapping" anchor="list_sp">
<section title="RFC3748" anchor="cplist3748">
<t>
Non-ASCII space characters [StringPrep, C.1.2] that can be mapped to SPACE (U+0020).
</t>
</section>
<section title="RFC4013" anchor="cplist4013">
<t>
Non-ASCII space characters [StringPrep, C.1.2] that can be mapped to SPACE (U+0020).
</t>
</section>
<section title="RFC4314" anchor="cplist4314">
<t>
Non-ASCII space characters [StringPrep, C.1.2] that can be mapped to SPACE (U+0020).
</t>
</section>
<section title="RFC4518" anchor="cplist4518">
<t>
Codepoints mapped to SPACE (U+0020) are following;
</t>
<t>
U+0009 (CHARACTER TABULATION)<vspace />
U+000A (LINE FEED (LF))<vspace />
U+000B (LINE TABULATION)<vspace />
U+000C (FORM FEED (FF))<vspace />
U+000D (CARRIAGE RETURN (CR))<vspace />
U+0085 (NEXT LINE (NEL))<vspace />
U+0020 (SPACE)<vspace />
U+00A0 (NO-BREAK SPACE)<vspace />
U+1680 (OGHAM SPACE MARK)<vspace />
U+2000 (EN QUAD)<vspace />
U+2001 (EM QUAD)<vspace />
U+2002 (EN SPACE)<vspace />
U+2003 (EM SPACE)<vspace />
U+2004 (THREE-PER-EM SPACE)<vspace />
U+2005 (FOUR-PER-EM SPACE)<vspace />
U+2006 (SIX-PER-EM SPACE)<vspace />
U+2007 (FIGURE SPACE)<vspace />
U+2008 (PUNCTUATION SPACE)<vspace />
U+2009 (THIN SPACE)<vspace />
U+200A (HAIR SPACE)<vspace />
U+2028 (Line Separator)<vspace />
U+2029 (Paragraph Separator)<vspace />
U+202F (NARROW NO-BREAK SPACE)<vspace />
U+205F (MEDIUM MATHEMATICAL SPACE)<vspace />
U+3000 (IDEOGRAPHIC SPACE)<vspace />
</t>
<t>
All other control code (e.g., Cc) points or code points with a
control function (e.g., Cf) are mapped to nothing.
Codepoints mapped to nothing that aren't specified by Stringprep are following;
</t>
<t>
U+0000-0008<vspace />
U+000E-001F<vspace />
U+007F-0084<vspace />
U+0086-009F<vspace />
U+06DD<vspace />
U+070F<vspace />
U+180E<vspace />
U+200E-200F<vspace />
U+202A-202E<vspace />
U+2061-2063<vspace />
U+206A-206F<vspace />
U+FFF9-FFFB<vspace />
U+1D173-1D17A<vspace />
U+E0001<vspace />
U+E0020-E007F<vspace />
</t>
</section>
</section>
<section title="Code points list for local case mapping" anchor="LCM-list">
<t>
Followings are a list of characters that need Local case mapping.
Format:<vspace />
<Language>; <Codepoint>; <Lowercase>; <Comments><vspace />
<Language> means the alpha-2 codes in <xref target="ISO.3166-1"/>.
</t>
<section title="Unidode 6.2">
<t>
<list>
<t>lt; 0049; 0069 0307; LATIN CAPITAL LETTER I<vspace />
lt; 004A; 006A 0307; LATIN CAPITAL LETTER J<vspace />
lt; 012E; 012F 0307; LATIN CAPITAL LETTER I WITH OGONEK<vspace />
lt; 00CC; 0069 0307 0300; LATIN CAPITAL LETTER I WITH GRAVE<vspace />
lt; 00CD; 0069 0307 0301; LATIN CAPITAL LETTER I WITH ACUTE<vspace />
lt; 0128; 0069 0307 0303; LATIN CAPITAL LETTER I WITH TILDE<vspace />
tr; 0130; 0069; LATIN CAPITAL LETTER I WITH DOT ABOVE<vspace />
tr; 0049; 0131; LATIN CAPITAL LETTER I<vspace />
az; 0130; 0069; LATIN CAPITAL LETTER I WITH DOT ABOVE<vspace />
az; 0049; 0131; LATIN CAPITAL LETTER I</t>
</list>
</t>
</section>
</section>
<section title="Change Log" anchor="changes">
<section title="Changes since -00">
<t>
<list style="symbols">
<t>
Modify the <xref target="lcm"/> "Local case mapping" to specify the method to calculate codepoints that local case mapping targets.
</t>
<t>
Add the <xref target="oi"/> "Open issues".
</t>
<t>
Modify the <xref target="iana"/> "IANA Considerations".
</t>
<t>
Modify the <xref target="sec"/> "Security Considerations".
</t>
<t>
Remove the "The initial precis local case mapping registrations".
</t>
<t>
Add the <xref target="LCM-list"/> "Code points list for local case mapping".
</t>
<t>
Add the <xref target="changes"/> "Change Log".
</t>
</list>
</t>
</section>
</section>
</back>
</rfc>
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