[$index]   -> [$index_of{Strand}]
[$index+1] -> [$index_of{Type}]
[$index+2] -> [$index_of{Pos}]

##</code><code>##

@index_of{@headers} = 0 .. $#headers;

##</code><code>##

#!/usr/bin/env perl -l

use strict;
use warnings;

my @test_headers = (
    [qw{Strand Type Pos Length Form Adjustment}],
    [qw{ID Strand Type Pos Length Form Adjustment}],
    [qw{Strand XXX Type Pos Length Form Adjustment}],
    [qw{Pos Type Length Strand Form Adjustment}],
);

for (@test_headers) {
    my @headers = @$_;
    my %index_of;
    @index_of{@headers} = 0 .. $#headers;
    print "Headers:      @headers";
    print "Strand index: $index_of{Strand}";
    print "Type index:   $index_of{Type}";
    print "Pos index:    $index_of{Pos}";
}

##</code><code>##

Headers:      Strand Type Pos Length Form Adjustment
Strand index: 0
Type index:   1
Pos index:    2
Headers:      ID Strand Type Pos Length Form Adjustment
Strand index: 1
Type index:   2
Pos index:    3
Headers:      Strand XXX Type Pos Length Form Adjustment
Strand index: 0
Type index:   2
Pos index:    3
Headers:      Pos Type Length Strand Form Adjustment
Strand index: 3
Type index:   1
Pos index:    0