B<SSL_ERROR_WANT_READ> or B<SSL_ERROR_WANT_WRITE>, it must be repeated
with the same arguments.
+When calling SSL_write() with num=0 bytes to be sent the behaviour is
+undefined.
+
=head1 RETURN VALUES
The following return values can occur:
The write operation was successful, the return value is the number of
bytes actually written to the TLS/SSL connection.
-=item 0
+=item Z<>0
The write operation was not successful. Probably the underlying connection
was closed. Call SSL_get_error() with the return value B<ret> to find out,