#!/usr/bin/env perl

use strict;
use warnings;

my @filter;

my $line = <DATA>;
#open (my $ffile, '<','filterfile') or die "cannot open filterfile: $!
+";
#my $line = <$ffile>;
#while ($line = <$ffile>) {
while ($line = <DATA>) {
    chomp $line;
    my ($col,$rel,$val,$foa,$ord) = split /\s+/,$line;
    $filter[$ord] = [ $col,$rel,$val,$foa ];
}

for my $ord (1 .. 3) {
    print "$ord:\n",
          "\tcol: "   ,$filter[$ord]->[0],"\n",
          "\trsh: "   ,$filter[$ord]->[1],"\n",
          "\tvalue: " ,$filter[$ord]->[2],"\n",
          "\tf_o_a: " ,$filter[$ord]->[3],"\n\n";
}

__DATA__
column relationship value filter_or_append order
a      <=           0.3   filter           1
b      =            abc   append           3
c      <=           0.3   filter           2
[download]

Each element of @filter is a reference to an anonymous array which contains values: [...].

Produces:

1:
    col: a
    rsh: <=
    value: 0.3
    f_o_a: filter

2:
    col: c
    rsh: <=
    value: 0.3
    f_o_a: filter

3:
    col: b
    rsh: =
    value: abc
    f_o_a: append
[download]