What does the various types of timeout specifications mean in 'Wait for JMS Queue Message' mean?

receiverTimeout - advance tab
Specifies the polling interval to check for new messages.
This default interval is set by the custom engine property bw.plugin.jms.receiverTimeout.
If no value is specified for the property, the default polling interval is one second.
Explanation: Checks for new message at Queue for each specified interval time.

Event Timeout (msec) A message may arrive before this activity is executed.
This field specifies the amount of time (in milliseconds) a message waits if it is received before this activity is executed.
If the event timeout expires, an error is logged and the event is discarded.
If no value is specified in this field, the message waits indefinitely.
If zero is specified, the event is discarded immediately, unless this activity has already been executed
Explanation: Messages will be in the queue as specified(Event timeout) time. After reaching this waiting period, message will be elapsed from the queue.

processTimeout integer The time (in milliseconds) to wait for the incoming message.
An error is returned if the message is not received in this time limit. 
Explanation: Time to wait for the messages, upon reaching the time limit, an error transition is returned out of this activity