>perl -E '$x=q[Category("notestrecord")];@a=split "",$x;say join "" => sort grep { !$seen{$_}++ } @a'
"()Cacdegnorsty
>

##</code><code>##

>perl -e 'print "$_\n" for (qr/ab.c/,qr/ab.c/i,qr/ab.c/s,qr/ab.c/si)'
(?^:ab.c)
(?^i:ab.c)
(?^s:ab.c)
(?^si:ab.c)
>

##</code><code>##

>perl -E 'say for (qr/ab.c/,qr/ab.c/i,qr/ab.c/s,qr/ab.c/si)'
(?^u:ab.c)
(?^ui:ab.c)
(?^us:ab.c)
(?^usi:ab.c)
>

##</code><code>##

>perl -e 'print "$_\n" for (qr/[abc]/,qr/[aabbcc]/,qr/[abcabc]/,qr/[cccbba]/)'
(?^:[abc])
(?^:[aabbcc])
(?^:[abcabc])
(?^:[cccbba])
>perl -E 'say for (qr/[abc]/,qr/[aabbcc]/,qr/[abcabc]/,qr/[cccbba]/)'
(?^u:[abc])
(?^u:[aabbcc])
(?^u:[abcabc])
(?^u:[cccbba])
>perl -e 'print "$_\n" for (qr"[abc]",qr"[aabbcc]",qr"[abcabc]",qr"[cccbba]")'
(?^:[abc])
(?^:[aabbcc])
(?^:[abcabc])
(?^:[cccbba])
>