What's SRV_PLT defined as?

I defined a new out of range index3 in the following example -

#!/usr/bin/perl -w
#use strict;
use Data::Dumper;

use constant index1 => 18;
use constant index2 => 19;
use constant index3 => 20;

my $rec = [
          618,
          'xxxxxxxxxx',
          '3-Moderate',
          'Normal',
          'Closed',
          'xxxxxxxxxx',
          'xxxxxxxxxx',
          'Approved',
          'Approved',
          '05/12/03 10:00',
          '02/12/03 09:45',
          '3.00',
          'Successful',
          '12/12/03 09:53',
          '05/12/03 13:00',
          '05/12/03 09:52',
          'Midrange',
          'Production',
          'CSC.MIDRANGE.SERVER.SUPPORT',
          1
        ];
# @$rec = map { defined($_) ? $_ : '' } @$rec;
# print Dumper($rec);

if ( defined $rec->[index1] &&
     $rec->[index1] ne '' &&
     defined $rec->[index2] &&
     $rec->[index2] eq '1' )
{
    if ($rec->[index3] == 1) { print "Crap\n" };                    # 
+39
    print "$rec->[index1] $rec->[index2] ", $rec->[index3], "\n";   # 
+40
    print "OK\n";
} else {
    print "Not OK\n";
}

# print Dumper($rec);
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And the output of an out of range index3:

Use of uninitialized value at ./p09.pl line 39.
Use of uninitialized value at ./p09.pl line 40.
CSC.MIDRANGE.SERVER.SUPPORT 1
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