[Tutorial] Filtering a trigger
For years i have been unaware and confused how people manage to make it so that 1 trigger can only be triggered by certain objects such as only a storage cube and a npc_zombie.
Only recently i have discovered how to make this function which is by using a point-entity called filter_activator_name.
On all brush-entities that have the option of "Filter Name" in the list, this is what only can trigger the entity including the flags in the brush-entity.
The way to make a filtered trigger is by creating a point-entity and make it a filter_activator_name and change the Filter_Name to the name of the entities you wish to activate the trigger.
If you want multiple entities with different names to activate the trigger then put in an asterisk ( * ) to where you want the rest of the entities to pass through; such as if the Filter_Name was Prop*, then anything with the name Prop at the beginning of it's name will pass through.
Below is a small graph of what only can pass the filter if the Entities beginning of the name is Prop.
What about *prop*? Would that effect "NPC_prop_funk"?
Any entity that has their name beginning with prop will will pass the filter.
EDIT:
Not sure if the *prop* will work, never tried it.
I'm guessing * is a simple wildcard, so it ought to work (though I haven't tried it).
*prop* would work, the filtering system works just like any other wildcard selection. You could also do something like "room_lock_0?_sprite" and use the question mark as a single character wildcard.
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I didn't know that symbol.
We need a topic for all these wild card and console commands sch as !self and so on... i would make it but i'm off to bed now so i'll make it tomorrow if no one else has 
what is the activator name if the player activates a trigger?
What? Can you rephrase the question, please?
Why does this need a tutorial? All you will ever need to know about this can be found over at developer.valvesoftware.com
!player and anything that activates it is !activator