The Japanese calendar uses an era name based on the accession time of
the current emperor.
The current emperor is planning to abdicate next month. That means that
a new era name will be devised. Unicode is planning a special release,
12.1, to cope with this.
This release adds a single character and associated properties.
The reason Perl is affected is because the timing of this might
otherwise prevent us from shipping 12.1 in Perl 5.30.
My claim is that the risk of adding this are so slight that we should
include it. The dates are uncertain, but I saw something that indicated
early April. But I can't find that now. Instead, I see May 7 as the
12.1 release date.
I'm writing this now so that we can come to a determination of what Perl