[idn] Re: Unicode categories

[John C Klensin <[e-mail]>]

--On Saturday, 12 March, 2005 01:14 -0800 Erik van der Poel
<[e-mail]> wrote:

> All,
> 
> Please do not draw any conclusions from the raw Unicode
> category stability data that I sent earlier. Ken Whistler, a
> Technical Director at the Unicode Consortium, was so kind to
> provide further information to put the data into their proper
> perspective. See below.
>...

Erik, Ken, and others,

The difficulty here is not, IMO, the specific numbers or
percentages.  It is an important difference in perspective.
>From the standpoint of UTC, these changes are few, minor, and
corrections to obscure errors.  That is a perfectly sensible
position.  

>From the standpoint of the IETF, or anyone else worried about a
piece of protocol that must support many applications, the
problem is a little different.  Some of the recent developments
in automatic updating tools notwithstanding, IDNA (and its
supporting tables) are designed to be embedded in and used from
clients.  Many of those clients, and the associated operating
systems, have been historically updated only when the machine in
which they run is replaced.   That argues for an extremely
conservative view of protocol design and compatibility, with
very high thresholds for justifying incompatible changes of any
sort.  From that viewpoint, the differences between 0.01%
changes and 5% changes is like measures of being partially
pregnant: perhaps helpful in some types of risk assessment, but
less so in making the next design decision.  

      john