I-D Action:draft-faltstrom-5892bis-02.txt

[Simon Josefsson]

Patrik Fältström <patrik at frobbit.se> writes:

> On 21 feb 2011, at 21.58, Simon Josefsson wrote:
>
>> I didn't understand John's argument that we have an incompatibility
>> regardless of what we do
>
> Either we have stability in the algorithm (as now proposed) or we have
> stability in the table which is the result of the calculation of the
> algorithm.
>
> IDNA2008 is defined as being an _algorithm_ that should be stable, so
> an application can apply it regardless of what version of Unicode we
> talk about.
>
> Because the algorithm is based on property values that now changes for
> three codepoints, the result of the calculation is not stable.
>
> The alternative would be to change the algorithm, and that would make
> the codepoints not change, but the algorithm changes.
>
> IDNA2003 was a table based solution.
>
> IDNA2008 is an algorithm based solution.

I don't follow this -- Mark is not proposing to change the algorithm.
If I understand him, he proposes to add U+19DA to section G in order to
make the IDNA2008 algorithm produce stable results independent of
Unicode version.

Again, what practical incompatibility is there in following Mark's
proposal?  An illustration would go a long way to convince me here, as I
believe Mark has illustrated that by _not_ adding another exception to
the list of exceptions, we will create two incompatible IDNA2008
algorithms: IDNA2008 with Unicode 5.2/6.0 vs IDNA2008-with-RFC5892bis
with Unicode 6.0.

/Simon