+PH/11 If retry_interval_max is set greater than 24 hours, it is quietly reset
+ to 24 hours. This avoids potential overflow problems when processing G
+ and H retry rules, and it seems reasonable to require a retry at least
+ once a day.
+
+PH/12 When the plaintext authenticator is running as a client, the server
+ challenges are now checked to ensure they are valid base64 strings. The
+ default action on failure is to abort the authentication. However, if
+ client_ignore_invalid_base64 is set true, invalid responses are ignored.
+
+PH/13 When the plaintext authenticator is running as a client, the challenges
+ from the server are placed in $auth1, $auth2, etc. as they are received.
+ Thus, the challege that is received in response to sending the first
+ string (with the AUTH command) can be used in the expansion of the second
+ string, and so on. Currently, up to 3 challenge strings are available in
+ this way. If an invalid base64 string is received when client_ignore_
+ invalid_base64 is set, an empty string is put in the $auth<n> variable.
+