Event:PARTY MEMBER CHANGED

Triggered when something in the party changes. 
These are the causes I've found for this event:
*Player joins party
*Player leaves party
*Player changes class
*Player gains a level up
*Player goes online/offline
arg1 
sometimes text of what has happened e.g. "[Player] joins the party" or "Class change to: <Primary> Lv<nn><Secondary> Lv<nn>" 
arg2, arg3 and arg4 contain some values where I couldn't find any pattern or logic behind it.
At least, there seems to be no parameter that tells you what happened, so each time you receive this event, you have to check for yourself what really happened.
-BuffyS
(-Updated by Bizzarrus)