Tables: BackwardCompatible Maintanence

[Mark Davis]

In short:
1. There is no change to the algorithm.

2. Implementers already must get the context table from the IANA site in
order to implement IDNA2008. This would just mean that they'd also have to
get the Backwards Compatibility table at the same time.

3. Instructions to IANA would be roughly:
a. At each new version of Unicode, regenerate the tables (we already want
them to do this).
b. If any character that was PVALID according to the previous table becomes
not PVALID, then add it to the Backwards Compatibility table.

Does that help?

Mark


On Wed, Nov 19, 2008 at 18:55, Vint Cerf <vint at google.com> wrote:

> Patrik, Mark,
> taking both of your points.
>
> Mark,
>
> how would backward compatibility be expressed? What action would one want
> implementors to take to implement it? perhaps an example would inform the
> working group?
>
> vint
>
>
> NOTE NEW BUSINESS ADDRESS AND PHONE
> Vint Cerf
> Google
> 1818 Library Street, Suite 400
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> 202-370-5637
> vint at google.com
>
>
>
>
> On Nov 19, 2008, at 9:43 PM, Patrik Fältström wrote:
>
> On 19 nov 2008, at 10.17, Mark Davis wrote:
>
> BackwardCompatible MaintanenceChanges to BackwardCompatible are a
> completely
> different beast than adjustments to PVALID and DISALLOWED. The
> latter we can
> hope to never happen. But changes to BackwardCompatible
> MUST be done to preserve backwards compatibility, it is not an
> option! And
> we know that there is a non-zero likelyhood that this will happen
> with each
> Unicode version (every year or so).The BackwardCompatible list, like
> the
> Context Rules Registry, should be under the aegis of IANA, with
> precise and
> strict instructions to add exactly (all and only) those characters
> necessary
> to preserve backwards compatibility with each new version of
> Unicode. This
> is not a new concept: BCP 47 (RFC 4646) has a section describing
> exactly
> what to do with each new version of a source ISO standard. The textual
> changes to do this are small, and I can supply suggested text.
>
>
> Point taken.
>
> My suggestion is though that we wait with potentially doing this
> change until we actually have a point in time when we need to add
> something to this list.
>
> My action if wg chair does not tell me we have consensus for any other
> specific changes is to do nothing.
>
> *Minor*
>
> This document uses different reference names for the same documents,
> eg
> [TR15]. All of the IDNA2008 documents should use the same notation for
> common references.
>
>
> Synchronization of references is something we will do closer to time
> of publication.
>
>     Patrik
>
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>
>
>
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