Re: "Open Interchange"

>>>The private use area, and surrogates are critical for certain
>>>applications.
>
>What is "open interchange"?  If it means no prior coordination between sender
>and receiver other than "to use XML", then the private use areas of Unicode
>by definition cannot be used.  How would the receiver know what character
>has been received?

I would say that the above is a fair definition of "open interchange",
though with the ability to *discover* what character has been sent,
the latter part of the assertion is false. This is why I have been
hoping to get an infrastructure in place for that exact purpose.

(To those who are waiting in the wings: I will be starting a mailing list 
soon for discussion of this issue).

>Questions:  Is XML really intended only to be used for "open interchange"
>as so defined?  

I do not think so, though obviously, the Internet is an important target.

>Will the use of XML be prohibited when additional agreements are needed?

No.

>How would this be enforced, and what gain would accrue from enforcing it?

You cannot enforce this, so no benefit is gained.