The timestamp of the last value and the time at which the last value was
received may differ..
The first line's status number is the number of identifiers returned or less
than zero if an error occurred. Each of the following lines contains the
-update time as an epoch value and the identifier, separated by a space.
+update time as an epoch value and the identifier, separated by a space. The
+update time is the time of the last value, as provided by the collecting
+instance and may be very different from the time the server consideres to be
+"now".
Example:
-> | LISTVAL