Time limit on handshake, accept, and close operations:
This value whether or not there is a time limit, and the duration of that
time limit, for asynchronous handshake, accept, and close operations. If
this is equal to the value
none then there will be no time
limit. Otherwise, if any of the applicable operations takes longer than
this amount of time, the operation will be canceled and a timeout error
delivered to the completion handler.