Assosciated Alarm data ActiveData vs ClearedData

Hello,

I'm having an issue understanding some of the functions around associated alarm data. In the script that I'm referencing they use both alarmEvent.getClearedData() and alarmEvent.getActiveData(). I've tried searching around a bit and other than some API documentations and a couple threads on here, I've failed to understand what the difference between these two functions are. Anyone able to point me in the right direction or explain the difference?