sub components {
my ($self) = @_;
return undef if (C4::Context->preference('marcflavour') ne 'MARC21');
return if (C4::Context->preference('marcflavour') ne 'MARC21');
if (!defined($self->{_components})) {
my $marc = C4::Biblio::GetMarcBiblio({ biblionumber => $self->id });
-