password could be stored into the B<userdata> storage and the
pem_passwd_cb() only returns the password already stored.
+When asking for the password interactively, pem_passwd_cb() can use
+B<rwflag> to check, whether an item shall be encrypted (rwflag=1).
+In this case the password dialog may ask for the same password twice
+for comparison in order to catch typos, that would make decryption
+impossible.
+
Other items in PEM formatting (certificates) can also be encrypted, it is
however not usual, as certificate information is considered public.
Allow SSL_write(..., n) to return r with 0 < r < n (i.e. report success
when just a single record has been written). When not set (the default),
SSL_write() will only report success once the complete chunk was written.
+Once SSL_write() returns with r, r bytes have been successfully written
+and the next call to SSL_write() must only send the n-r bytes left,
+imitating the behaviour of write().
=item SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER