=over 4
-=item 0
+=item Z<>0
The shutdown is not yet finished. Call SSL_shutdown() for a second time,
if a bidirectional shutdown shall be performed.
The output of L<SSL_get_error(3)|SSL_get_error(3)> may be misleading, as an
erroneous SSL_ERROR_SYSCALL may be flagged even though no error occurred.
-=item 1
+=item Z<>1
The shutdown was successfully completed. The "close notify" alert was sent
and the peer's "close notify" alert was received.