You are correct. I was under the impression that a reference to @_ behaved differently than a reference to another localized array, once the localization went out of scope.

But the following example appears to show they behave the same...

use strict;
use Data::Dumper;

our @X;
my ($underscore, $scissors);

@_ = (1..3);
@X = (1..3);

sub foo {
    local @X = (4..6);
    $underscore = \@_;
    $scissors   = \@X;
}

foo(4..6);
print Dumper($underscore, $scissors);
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So (like $_) @_ is just a global array that gets localized by certain control structures. (In particular, sub.)