Wow..... I was way off.
Here is an update: 
#!/usr/local/bin/perl
use strict;

my %stock;
$stock{'128'} = [0,224,0,0];
$stock{'12'} = [0,0,15,0];
$stock{'8'} = [32,0,0,0];

while (<DATA>) {  ## file2
  my @data = split(',',$_);
  if (exists $stock{$data[0]}) {
    my $ary_ref = $stock{$data[0]};
    my ($sm,$md,$lg,$xl) = @$ary_ref;

    if($sm eq '0'){$sm=''}else{$sm=0};
    if($md eq '0'){$md=''}else{$md=0};
    if($lg eq '0'){$lg=''}else{$lg=0};
    if($xl eq '0'){$xl=''}else{$xl=0};


    $data[9]  = $sm;
    $data[12] = $md;
    $data[15] = $lg;
    $data[18] = $xl;
  }
  print (join(',', @data));
}

__DATA__
128,1,Download,0,,TEXT,2,Size,2,??,SM,3,??,MD,4,??,LG,5,??,XL
12,1,Download,0,,TEXT,2,Size,2,??,SM,3,??,MD,4,??,LG,5,??,XL
8,1,Download,0,,TEXT,2,Size,2,??,SM,3,??,MD,4,??,LG,5,??,XL

[download]
What's scary is.... I Almost understand it.
Thanks to everyone that replied.

In reply to Re^2: Parsing and modifying CSV files by ch1
in thread Parsing and modifying CSV files by ch1

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