Task closing rules help administrators mandate task-related fields which they consider as significant for the task. When task closing rules have been set up, the technicians working on the task will have to adhere to these rules; else an error message will be displayed prompting them to fill the mandatory fields.
For example, if you have set up Worklog as a mandatory field, the technicians will be able to complete tasks only after filling in the Worklog details.
To configure task closing rules,
>> Automation >> Closure rules >> Task Closure Rules tab on top. This opens the Task Closure Rules page.