my @fields = qw(
    opffile
    spec
    twig
    twigroot
    twigmeta
    error
    );
    
require fields;
fields->import(@fields);

##</code><code>##

my @fields = qw(
    opffile
    spec
    twig
    twigroot
    twigmeta
    error
    );
    
use fields @fields;