# provided by the outermost if
$1 = undef;
$2 = undef;
$3 = undef;
{ # provided by the inner if
   $1 = 'aa';
   $2 = 'bb';
   $3 = 'cc';
}

##</code><code>##

$_ = "aabbccdd";
if ( /^(\w\w)\w\w(\w\w)\w\w$/ ) {
    if ( /^\w\w(\w\w)\w\w(\w\w)$/ ) {
        print "inner: $1 $2\n";
    }
    print "mid: $1 $2\n"; # the inner if's vars are still accessible here
}
print "outer: $1 $2\n";

##</code><code>##

$_ = "aabbccdd";
/^(\w\w)\w\w(\w\w)\w\w$/;
{
    /^\w\w(\w\w)\w\w(\w\w)$/;
    {
        print "inner: $1 $2\n";
    }
    print "mid: $1 $2\n";
}
print "outer: $1 $2\n";