C1 are part of ISO-8859-1 (as far as the IANA is concerned)

[SoniEx2]

https://en.wikipedia.org/wiki/ISO/IEC_8859-1

"ISO-8859-1 is the IANA preferred name for this standard when supplemented with the C0 and C1 control codes from ISO/IEC 6429"

(Python didn't get the memo)