+RSA_set_method() returns a pointer to the old RSA_METHOD implementation
+that was replaced. However, this return value should probably be ignored
+because if it was supplied by an ENGINE, the pointer could be invalidated
+at any time if the ENGINE is unloaded (in fact it could be unloaded as a
+result of the RSA_set_method() function releasing its handle to the
+ENGINE). For this reason, the return type may be replaced with a B<void>
+declaration in a future release.
+
+RSA_new_method() returns NULL and sets an error code that can be obtained
+by L<ERR_get_error(3)|ERR_get_error(3)> if the allocation fails. Otherwise
+it returns a pointer to the newly allocated structure.
+
+=head1 NOTES
+
+As of version 0.9.7, RSA_METHOD implementations are grouped together with
+other algorithmic APIs (eg. DSA_METHOD, EVP_CIPHER, etc) into B<ENGINE>
+modules. If a default ENGINE is specified for RSA functionality using an
+ENGINE API function, that will override any RSA defaults set using the RSA
+API (ie. RSA_set_default_method()). For this reason, the ENGINE API is the
+recommended way to control default implementations for use in RSA and other
+cryptographic algorithms.
+
+=head1 BUGS
+
+The behaviour of RSA_flags() is a mis-feature that is left as-is for now
+to avoid creating compatibility problems. RSA functionality, such as the
+encryption functions, are controlled by the B<flags> value in the RSA key
+itself, not by the B<flags> value in the RSA_METHOD attached to the RSA key
+(which is what this function returns). If the flags element of an RSA key
+is changed, the changes will be honoured by RSA functionality but will not
+be reflected in the return value of the RSA_flags() function - in effect
+RSA_flags() behaves more like an RSA_default_flags() function (which does
+not currently exist).