sub EVENT_SPAWN 
{
This works very well and I use it a lot in my server, basically to explain it..
Whenever a mob spawns, you can make him do something, for example, set off a timer or signal another NPC, I will show you below.
	Code:
	sub EVENT_SPAWN
{
quest::shout("I have spawned!");
quest::signal(152);
quest::settimer("a", 200);
quest::settimer("b", 400);
quest::settimer("c", 600);
}
sub EVENT_TIMER
{
if($timer == a)
        {
         quest::stoptimer("a");
         quest::shout("Timer A Complete!");
}
if($timer == b)
         {
         quest::stoptimer("b");
         quest::shout("Timer B Complete!");
}
if($timer == c)
         {
          quest::stoptimer("c");
          quest::shout("Timer C Complete!");
}
}
 That is just a random example with what you can do with spawn... Hope my information helped, also..
sub EVENT_ENTER, I have no idea what this does if it even does work...
Edit:
I did some research for you and found that Fathernitwit had added these, shown in the change log below.
	Quote:
	
	
		| 
			
				FatherNitwit: Proximity quests: added events: EVENT_ENTER, EVENT_EXIT
			
		 | 
	
	
 FatherNitWit wrote a tutorial on Proximity quests, here is the link 
FatherNitWits Proximity Tutorial 
Note: All I did was type EVENT_ENTER in the search window and it took me to this, just a little insight in the future, try using search first 

 Ofcourse there is never any harm in asking though