The Unicode code points and IDNA - Unicode 6.0
draft-faltstrom-5892bis-00.txt

Abstract

This document specifies updates Section 2.7 of RFC 5892 so that the calculation of the rules are backward compatible when Unicode 6.0 is released.

Status of this Memo

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Table of Contents

1.  Introduction
2.  New section 2.7
    2.1.  BackwardCompatible (G)
3.  IANA Considerations
    3.1.  IDNA derived property value registry
4.  Security Considerations
5.  Acknowledgements
6.  References
    6.1.  Normative References
    6.2.  Informative References
§  Author's Address

1.  Introduction

RFC 5892 (Faltstrom, P., “The Unicode Code Points and Internationalized Domain Names for Applications (IDNA),” August 2010.) [RFC5892] specifies an algorithm that based on The Unicode Standard (The Unicode Consortium, “The Unicode Standard, Version 6.0.0,” 2010.) [Unicode6] defines a derived property value. Unicode 6.0 have one codepoint that has changed GeneralCategory which implies the codepoint would move from PVALID to DISALLOWED.

This document updates section 2.7 Backward Compatible and adds the codepoint U+19DA NEW TAI LUE THAM DIGIT ONE to it.

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 (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.) [RFC2119].

2.  New section 2.7

Between Unicode 5.2 and 6.0, three codepoints have changed in a non-compatible way. U+0CF1 and U+0CF2 move from DISALLOWED to PVALID, and can be treated as codepoints that move from UNASSIGNED to PVALID. U+19DA moves from PVALID to DISALLOWED due to a change of GeneralCategory from Nd to No. This new section 2.7 has added U+19DA for backward compatibility reasons.

2.1.  BackwardCompatible (G)

G: cp is in {19DA}

This category includes the code points that property values in versions of Unicode after 5.2 have changed in such a way that the derived property value would no longer be PVALID or DISALLOWED. If changes are made to future versions of Unicode so that code points might change property value from PVALID or DISALLOWED, then this table can be updated and keep special exception values so that the property values for code points stay stable.

PVALID -- Would otherwise have been DISALLOWED

19DA; PVALID     # NEW TAI LUE THAM DIGIT ONE

3.  IANA Considerations

3.1.  IDNA derived property value registry

IANA is to update the algorithm used for derived property value registry to reflect this change in the algorithm.

4.  Security Considerations

If algorithm presented in RFC 5892 (Faltstrom, P., “The Unicode Code Points and Internationalized Domain Names for Applications (IDNA),” August 2010.) [RFC5892] is applied to Unicode 6.0 without adding the change described in this document, the codepoint U+19DA will have the wrong derived property value. That in turn will make the codepoint DISALLOWED instead of PVALID.

5.  Acknowledgements

The main contributors are (in alphabetical order) Eric Brunner-Williams, Vint Cerf, Tina Dam, Mark Davis, Paul Hoffman, John Klensin, Pete Resnick, Markus Scherer, Andrew Sullivan, Kenneth Whistler and Nicholas Williams.

6.  References

6.1. Normative References

6.2. Informative References

Author's Address