Upside-down: these are documents which currently break on existing parsers, and it would be good if they didn't.

Whether it is utf-8+names or xml1.2  or some default mode for parsers that could be enabled or disabled, the
choice should be the data providers: just like now, if they want to use iso8859-1 encoding, the user (data provider)
is the best person to decide the tradeoffs of another system not being able to handle it. Not committees trying
to keep the world pure! 

Cheers
Rick