Read carefully
If you're not familiar with JIRA Events please read it carefully to discover full SLA PowerBox potential.
JIRA Event is a message that issue sends to all JIRA backgroud processed when a change on the issue is performed. Event, once fired, can be processed by multiple backgroud processes (called listeners) such as email sending listener or SLA listener.
Any change performed on an JIRA issue creates a corresponding issue event. E.g. if you create an issue, Issue Created event is fired. JIRA mechanism in dependent on the issue events. They inform the system that something has happened and trigger appropriate actions within JIRA.
The two types of issue events in JIRA are:
System events that are fired by JIRA internally. They cannot be changed or deleted but can be used by workflow designers outside of standard actions.
Tip: You can make system events inactive. - Custom events - are defined by system administrators and used in workflow transitions.