M-label definition

[Mark Davis]

I agree. Formally, either choice of definition could work (including or
excluding U-Label). In terms of exposition, however, I think the simplest
choice of terminology is that M-Label is anything that maps to a U-Label,
including the identity mapping. So M-Label is a superset of U-Label.

Mark


On Wed, Apr 8, 2009 at 06:52, Eric Brunner-Williams <
ebw at abenaki.wabanaki.net> wrote:

> that was my understanding, U is a subset of M.
>
> Vint Cerf wrote:
> > won't making M-label a subset of U-label destroy an important property
> > of U-label as defined in IDNA2008?
> >
> > Under IDNA2008 there is a one-to-one mapping of every U-label to A-
> > label and vice-versa, without any mapping.
> >
> > M-label needs mapping to become a U-label and is thus a superset, I
> > believe.
> >
> > Vint Cerf
> > Google
> > 1818 Library Street, Suite 400
> > Reston, VA 20190
> > 202-370-5637
> > vint at google.com
> >
> >
> >
> >
> > On Apr 7, 2009, at 11:27 PM, YAO Jiankang wrote:
> >
> >
> >> ----- 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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> >>>> Idna-update at alvestrand.no
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> >>>>
> >>>>
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> >>>
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> >
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> >
> >
>
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