A quick tip on the Classic Workflow and Transitions, in response to a query that came in today.
How to stop the Status of a Classic Workflow Task moving to "Complete" if the Change Order's Assignee is empty?
Use the Workflow "Transitions" which are available under Behaviors against each Workflow Status.
The part which may not be obvious is that these Transition conditions apply to the Statuses *prior* to the one you wish to impact.
That is, if you wish to do your conditional check at the time the Status = Complete, you need to set the transitions against "Pending" and any other Status that may be prior to "Complete."
Naturally, you won't need to put the conditions on "Cancelled" or a Status which means that Complete won't be reached.
You'll find these under Administration, Service Desk, Categories, Classic Workflow, Behavior, Transition Information.
For a very rough draft document of screenshots showing these steps, please see the attached.
Hope this helps someone for Classic Workflow, even though CA Process Automation is taking over for more complex Workflow needs.