sub wertX {
    my $self = shift;
    if( @_ ) {
        if( $_[0] =~ /^[wb]$/ ) {
            $self->container->[11] = $_[0];
        }
        else {
            confess "Invalid value $_[0] for attribute wertX";
        }
    }
    return $self->container->[11] //= 'w'; # defaultwert
}