+=head1 NOTES
+
+The BIO_lookup_ex() implementation uses the platform provided getaddrinfo()
+function. On Linux it is known that specifying 0 for the protocol will not
+return any SCTP based addresses when calling getaddrinfo(). Therefore if an SCTP
+address is required then the B<protocol> parameter to BIO_lookup_ex() should be
+explicitly set to IPPROTO_SCTP. The same may be true on other platforms.
+
+=head1 HISTORY
+
+The BIO_lookup_ex() function was added in OpenSSL 1.1.1.
+