Because it's not a regex flag, per se. It's a pattern matching operator flag. perlre only covers /i, /m, /s, and /x.
Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart

In reply to Re^3: search hang trouble by japhy
in thread search hang trouble by greatdane

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