title: Should exceptions be defined in use cases?
body: <p>Say you have a use case called 'schedule meeting.' Defined in the spec, meetings can only be scheduled for the current time or the future. In the Use Case should it include the flow where "if the date/time given is in the past, a message box will show 'meeting time cannot be in the past'"?</p>
  
  <p>Like I said, it's defined in the spec that the date/time cannot be in the past, but in the use case definition, should it be defined there as well?</p>