#!/usr/bin/perl

# https://perlmonks.org/?node_id=1231482

use strict;
use warnings;

while(<DATA>) 
  {
  chomp;
  my ($colA, $colB, $colC, $colD) = split /\s{2,}/;
  $colD =~ /Region/ and $colC =~ s{^XYZ\z}{N/A};
  use Data::Dump 'dd'; dd $colA, $colB, $colC, $colD;
  }

__DATA__
ValuesInColumn1    DataColumnB    XYZ    RowDescription|RowCode|Supplier ID::Region
ValuesInColumn1    DataColumnB    XYZ    RowDescription|RowCode|Supplier ID::Region
ValuesInColumn1    DataColumnB    XYZ    RowDescription|RowCode|Supplier ID::Region
ValuesInColumn1    DataColumnB    XYZ    RowDescription at RowCode
ValuesInColumn1    DataColumnB    ABC    RowDescription at RowCode