On Thu, Aug 1, 2013 at 9:46 PM, MRAB <python@mrabarnett.plus.com> wrote:
We could follow Perl or Ruby, or both of them, or even allow braces
with any of the hex escapes.

That choice is unfortunately precluded by backwards compatibility because both "\u1FFFF" and "\x1FFFF" are valid strings. (Are braces optional in Perl's \x{..} or Ruby's \u{..}?) 

Also, the upper-case U is more in-line with U+ notation and \N escape.  If we are looking for "one obvious way," I think it should be \U with \x and \u remaining the other less obvious ways.