Just to clarify things in my mind, would the following be allowed
in your world?  HTTP headers followed by HTML document:
	HTTP/1.0 200 OK
	Date: Saturday, 29-Apr-95 03:53:33 GMT
	Server: ...
	MIME-version: 1.0
	Content-Type: text/html; charset=iso-2022-jp
	Last-modified: Tuesday, 18-Apr-95 16:10:13 GMT
	Content-length: 15132
	<TITLE>...</TITLE>
	<BODY>
	Here is some normal text.
	Here is a 10646 numerical entity: �.
	Here is some ISO-2022-JP text: ...
	</BODY>
I.e. is the charset allowed to be iso-2022-jp (or any other non-Latin-1
and non-10646/Unicode charset), and are you still allowed to use 10646
numeric entities within such documents?
If this is allowed, I agree that this would be a good way to migrate
to the Brave New World of 10646.
Erik