Stop me if I've misunderstood...

[Shawn Steele]

>> If you want to make a run at a concise definition, that would be still be most
>> appreciated, at least by me.

Thinking...

Does this work?

"An interoperable IDNA system is one where a human readable machine name from any source, entered by any user, in any country or language, on any computer platform or software, will resolve to the identical IP address with minimum disruption of user expectations."

Maybe I tried to say too much and made it all murky.

It doesn't specifically say "Opera users can visit an IIS server on a connection containing Cisco routers."  But that's what hopefully computer platforms is.

"Human readable name" is not intended to say they have to be words.  Commonly users expect words, but words aren't always possible (already taken, mapped to something else, etc.)

"minimum disruption of user expectations" is how I address users expecting some mappings.  "minimum disruption" considers that some conflicting user expectations (Turkish i) are unavoidable.

As Mark's note points out viewpoints, mine is from the client/user perspective, although I don't think this language disagrees with what the registrar perspective has been stating.

Don't know if you find that helpful, and please don't nitpick every word, I'm sure it has holes!

-Shawn