sub createCopybooks
{
    my $self = shift;
    my @filterCodes = @_;
    
    my %copyBooks;
    foreach my $filterCode ( @filterCodes )
    {
        my $copyBook              = Cobol::Copybook->new({filehandle => \*DATA, filter => $filterCode} );
        my $copyBookName          = 'cpy' . $filterCode;
        $copyBooks{$copyBookName} = $copyBook;
    }
    
    $self->{copybooks} = \%copyBooks;
}