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From: Veek M <veekjunk@foobar.com>
Newsgroups: comp.lang.python
Subject: open: 'ascii', 'backslashreplace' not behaving as expected - why?
Date: Sat, 8 Aug 2026 00:38:24 -0000 (UTC)
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Xref: csiph.com comp.lang.python:197866

So in kate, i Ctrl-Shift-U and type ffff to enter a unicode codepoint  of 
0xffff. Then at the REPL prompt i do 
fh = open('/tmp/x', 'rt', -1, 'ascii', 'backslashreplace', None)

and i get 
fh.readline()
'\\xef\\xbf\\xbf\n'

Since I wrote two bytes 0xff and 0xff into Kate - why am i getting 0xef 
0xbf and 0xbf ?