# Copy the ISNI number over (should one exist) to subfield $o when linking

    # authorities with authorities in UNIMARC instances. This only applies to

    # the Personal Name, Corporate Body Name, and Family Name authority types.

    #

    # It's worth noting that the default MARC Authorities framework that ships

    # with UNIMARC Koha instances does *not* include a subfield $o for fields

    # 200 (Authorized Access Point - Personal Name),

    # 210 (Authorized Access Point - Corporate Body Name), and

    # 220 (Authorized Access Point - Family Name).

    # This is per the offical IFLA Manual, and effectively means we can save

    # the ISNI number in the @subfield_loop array without worrying about

    # overwriting any previous value that may exist.

    #

    # For more information, see the offical IFLA UNIMARC Authorities Format

    # Manual (online ed., 1.0.0, 2023), pp. 350, 363, 385.

    if ( C4::Context->preference('marcflavour') eq 'UNIMARC' ) {

        my $isnifield    = $record->field('010');

        my $isnisubfield = $isnifield->subfield('a') if defined $isnifield;

        my $isninumber   = $isnisubfield

            if defined $isnisubfield && ( $auth_type->auth_tag_to_report =~ /^(200|210|220)$/ );

        push( @subfield_loop, { marc_subfield => 'o', marc_values => $isninumber } ) if defined $isninumber;

    }