referencing IDNA2008 (and IDNA2003?)

=JeffH Jeff.Hodges at
Thu Oct 21 19:12:16 CEST 2010


In the httpstate, we've almost completed our spec on HTTP Cookies (as they 
actually are implemented & deployed). In the process, we've attempted to 
properly reference the IDNA specs, but of course with the recent publication of 
IDNA2008 and its obsoleting IDNA2003, this presented a bit of head-scratching 
WRT how to properly reference them since IDNA2008 is not backwards compatible 
and there's going to be a transition period for some time.

Below's what we came up with (the following are relevant excerpts from 

How does that look to you folks?


[ httpstate chair & document shepherd ]


5.1.2.  Canonicalized host names

    A canonicalized host name is the string generated by the following

    1.  Convert the host name to a sequence of NR-LDH labels (see Section of [RFC5890]) and/or A-labels according to the
        appropriate IDNA specification [RFC5891] or [RFC3490] (see
        Section 6.3 of this specification)

    2.  Convert the labels to lower case.

    3.  Concatenate the labels, separating each label from the next with
        a %x2E (".") character.


6.3.  IDNA dependency and migration

    IDNA2008 [RFC5890] supersedes IDNA2003 [RFC3490] but is not
    backwards-compatible.  For this reason, there will be a transition
    period (possibly of a number of years).  User agents SHOULD implement
    IDNA2008 [RFC5890] and MAY implement [Unicode Technical Standard #46
    <>] in order to facilitate a smoother
    IDNA transition.  If a user agent does not implement IDNA2008, the
    user agent MUST implement IDNA2003 [RFC3490].


10.  References

10.1.  Normative References


    [RFC3490]  Faltstrom, P., Hoffman, P., and A. Costello,
               "Internationalizing Domain Names in Applications (IDNA)",
               RFC 3490, March 2003.

               See Section 6.3 for an explanation why the normative
               reference to an obsoleted specification is needed.

    [RFC5890]  Klensin, J., "Internationalized Domain Names for
               Applications (IDNA): Definitions and Document Framework",
               RFC 5890, August 2010.

    [RFC5891]  Klensin, J., "Internationalized Domain Names in
               Applications (IDNA): Protocol", RFC 5891, August 2010.


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