> That way each PEP can argue as strongly as it can for the respective authors preferred approach to tackling the default C locale problem, even if they point to a common background section in one of the PEPs (similar to the way PEPs 522 and 524 shared a common problem definition, even though they proposed different ways of handling it).

Ok, same players play again: as PEP 522/524 with Nick and me, I just wrote the PEP 540 "Add a new UTF-8 mode" and Nick wrote the PEP 538 :-D

I started a thread to discuss the PEP on python-ideas:
https://mail.python.org/pipermail/python-ideas/2017-January/044089.html

IMHO the PEP 538 should discuss the usage of the surrogateescape error handler: see my second mail in the thread for the details.

I proposed a change in my 3rd mail which would move my PEP closer to Nick's PEP 538: enable "automatically" the UTF-8 mode when the locale is POSIX.