On 26.10.2020 18:05, STINNER Victor wrote:
> 
> By the way, Unicode 3.2 was released in 2002: 18 years ago. I don't think that it's still relevant in 2020 to keep backward compatibility with Unicode 3.2. I propose to deprecate unicodedata.ucd_3_2_0 and deprecate the unicodedate.UCD type. In Python 3.12, we will be able to remove a lot of code, and simplify the code a lot.

The version 3.2.0 is needed for IDNA compatibility:

IDNA 2003: https://tools.ietf.org/html/rfc3490
requires Unicode 3.2 mappings

IDNA 2008: https://tools.ietf.org/html/rfc5890 et al.
requires Unicode 5.2+ mappings

Python only supports IDNA 2003 AFAIK and the ucs_3_2_0 tag was added
by Martin von Löwis to support it even after moving forward to more
recent Unicode versions.

IDNA 2008 seems to have mechanisms to also work for Unicode versions
later than 5.2, but I don't know the details. See this TR for details
on how IDNA compatibility is handled:

http://www.unicode.org/reports/tr46/

All that said, it may actually be better to deprecate IDNA 2003 support
first and direct people to:

https://pypi.org/project/idna/

or incorporate this into the stdlib instead of IDNA 2003. The special
tag can then be dropped.

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