my @values = map {
        my $ch = $thingy->first_child( $_ );
        $ch ? $ch->text : ""
     } qw( DOCNUM MESTYP SNDPRN RCVPOR RCVPRN );
[download]

Also, as I mentioned, you probably don't need to create a new Twig and CSV objects for each file. Declaring the sub inside the loop makes no sense, either.

#!/usr/bin/perl
use warnings;
use strict;

use Text::CSV_XS;
use XML::Twig;

my $csv = 'Text::CSV_XS'->new({
    sep_char => '|',
});

sub process_EDI_DC40 {
    my ($twig, $thingy) = @_;

    my @values = map {
        my $ch = $thingy->first_child( $_ );
        $ch ? $ch->text : ""
    } qw( DOCNUM MESTYP SNDPRN RCVPOR RCVPRN );

    $csv->say(*STDOUT, \@values);
}

my $listfile = shift;
open my $list, '<', $listfile or die $!;

my $twig = 'XML::Twig'->new(
    twig_handlers => {
        EDI_DC40 => \&process_EDI_DC40,
    },
);

while (my $xmlfile = <$list>) {
    chomp $xmlfile;
    $twig->parsefile($xmlfile);
}
[download]

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]