M-label definition

[YAO Jiankang]

----- Original Message ----- 
From: "Erik van der Poel" <erikv at google.com>
To: "Paul Hoffman" <phoffman at imc.org>
Cc: <idna-update at alvestrand.no>; "John C Klensin" <klensin at jck.com>; "Lisa Dusseault" <lisa.dusseault at gmail.com>
Sent: Wednesday, April 08, 2009 10:19 AM
Subject: Re: M-label definition



>>> "An M-label is a string that can be mapped into a
>>> [valid] U-label. It may be a U-label, since those
>>> trivially map into themselves. The category of U-label
>>> is a proper subset of the category of M-label." (Mark
>>> and others).

> 
> So, one possibility for M-label is to make it correspond to an
> IDNA2003 "internationalized label", which would make the set of
> M-labels a superset of U-labels. (The other possibility mentioned by
> John is: [<set of U-labels> + <set of M-labels>] corresponds to <set
> of IDNA2003 internationalized labels>.)


another view:

[<set of U-labels> + <set of A-labels>] corresponds to <set of IDNA2003 internationalized labels> since IDNA2003 internationalized labels including all the forms of all valid IDNA2003 internationalized labels.

M-label is a subset of U-label instead of superset. M-label is a special U-label which must do some mapping before being transformed into A-label or doing some lookup.



YAO Jiankang





> 
> Does this make sense?
> 
> Erik
> 
> On Tue, Apr 7, 2009 at 5:31 PM, Paul Hoffman <phoffman at imc.org> wrote:
>> At 4:59 PM -0700 4/7/09, Lisa Dusseault wrote:
>>>I'm not certain a new term needs to be introduced. If we're talking
>>>about a string that is invalid as a label, giving it that term seems
>>>to legitimize it. If we're talking about a string that may or may not
>>>be valid, that's just "a string"
>>
>> Good catch. John's second option was:
>>

>>
>> When I supported it, I was thinking of it as "...a valid U-label", that is, without the "valid" being optional.
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