And what is: '(?^u:' ?

When inspecting (using the EPIC/Eclipse Perl debugger) the internal composition of a compiled regex (for example:

my $var = qr/abc/;

then $var shows as:

 '(?^u:abc)'

What is '(?^u:' ?

In reply to Re^6: Internal representation of qr//: and what is: "(?^u:" ? by HelenCr
in thread Internal representation of qr// compiled regular expressions by John M. Dlugosz

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