#!/usr/local/perl/bin/perl -w

use strict;
use Data::Dumper;

my $var;
my $hash = ();

$hash = {
   LEV11 => {
      LEV21 => {
         VAL1 => '123',
         VAL2 => ['1', '2', '3'],
         VAL3 => '456',
      },
      LEV22 => {
         VAL1 => '456',
         VAL2 => ['4', '5', '6'],
         VAL3 => '789',
      },
   },
   LEV12 => {
      LEV31 => {
         VAL1 => 'abc',
         VAL2 => ['a', 'b', 'c'],
         VAL3 => 'def',
      },
      LEV32 => {
         VAL1 => 'def',
         VAL2 => ['d', 'e', 'f'],
         VAL3 => 'ghi',
      },
   },
   LEV13 => {
      LEV41 => {
         VAL1 => 'abc',
         VAL2 => ['a', 'b', 'c'],
         VAL3 => 'def',
      },
      LEV42 => {
         VAL1 => 'def',
         VAL2 => ['d', 'e', 'f'],
         VAL3 => 'ghi',
      },
   },
};

print Dumper($hash);
$var = $hash->{LEV11}{LEV31}{VAL1} ||
       $hash->{LEV12}{LEV31}{VAL1} ||
       $hash->{LEV13}{LEV31}{VAL1};

print "VAR = $var\n";
print Dumper($hash);
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Why do I end up with a hash key $hash->{LEV11}{LEV31} after the $var = ... assignment, when that key did not exist originally? I'm assuming it has something to do with the || operators.