Sorry that I dig out this old thread again, but to me it seems that you never got an answer for your last question.

So its a Yes and a No.
c_scan only "finds" (reports) entities that have enable_scan set. Now you can also attach an event function to these entities if they should react on the c_scan event.
Imagine this:
You stand in a room and have a blindfold on. Now you ask: "Is there anyone here in a circle of 2 meters around me?" (c_scan) and then the person standing next to you answers "yes" (you is set to that person).
Now you know there is someone and you can adress him (the you pointer).
From here on your can use that information (someone answered and who answered) to do something.
That would be what the scanning-entity would do.
Now if you tell all thoses people in the room that they should do something when you ask, that would be the event function.

Hope this makes it a more clear.