I guess I'm trying to understand your question. A meeting being agreed to by both parties is what determines whether a meeting has been organized in advance or not, and it doesn't have to be in a meeting room; it can be anywhere.
As I said previously, if someone were to see you going into the lounge or something and asked to talk to you, I would say that's an oral meeting and they have now arranged it, if you agree to sit with him or her.
So whether you ask to see them or they ask to see you, there's still an encounter.