+When looking up CA certificates, the OpenSSL library will first search the
+certificates in B<CAfile>, then those in B<CApath>. Certificate matching
+is done based on the subject name, the key identifier (if present), and the
+serial number as taken from the certificate to be verified. If these data
+do not match, the next certificate will be tried. If a first certificate
+matching the parameters is found, the verification process will be performed;
+no other certificates for the same parameters will be searched in case of
+failure.
+
+=head1 WARNINGS
+
+If several CA certificates matching the name, key identifier, and serial
+number condition are available, only the first one will be examined. This
+may lead to unexpected results if the same CA certificate is available
+with different expiration dates. If a "certificate expired" verification
+error occurs, no other certificate will be searched. Make sure to not
+have expired certificates mixed with valid ones.
+