If the Issue Substatus field is activated in your Administration > System > System Settings > Optional Fields, you can add Substatus Rules to automatically update issues to a different Substatus when certain events occur. For example, if an issue’s Substatus is User Response Needed, its Substatus could be updated to Under Review as soon as the Submitter adds a note. Among these types of Substatus Rules, there is also a Process Order that defines which Rule is to be applied when issues simultaneously qualify for multiple Substatus Rules.
Substatus Rules may also be used to pause the system clock when issues have certain Substatuses. Once the clock has been paused on an issue—its Adjusted Time Open (i.e. Total Time Open minus how long clock is/was paused) will be used for Escalations, SLAs and standard reports instead of its Total Time Open (i.e. exactly how long issue is/was open). For example, if the Substatus User Response Needed pauses the system clock, an issue with this Substatus would not continue to accrue Escalation or SLA processes until the Submitter adds a note or a user changes its Substatus.