the B<keep> argument is zero, this call disables the retention of file
descriptors. Conversely, a nonzero argument enables the retention of
file descriptors. This function is usually called during initialization
-and it takes effect immediately.
+and it takes effect immediately. This capability only applies to the default
+provider.
RAND_event() and RAND_screen() are equivalent to RAND_poll() and exist
for compatibility reasons only. See HISTORY section below.