There is an old joke sometimes attributed to Einstein: "If we knew what it was we were doing, it would not be called research, would it?"
As an example, I am frequently at a loss of how to rigorously define some informal concept. This is because I do not know what I am doing. But, if I knew what I was doing, it would not be called research, would it? OTOH, there are an infinite number of ways to take an informal concept and cast it into a rigorous framework, so this is a very "open-ended" type of question.
It seems to me that some of the StackExchange sites are geared toward research-level questions. For example, imho, MathOverflow is more researcher-oriented than Cross-Validated is more researcher-oriented than StackOverflow. As such, I am wondering how a "research-level" question doesn't involve some degree of open-endedness. Perhaps it is the case that I am taking the phrase "research-level" too literally, and it does not mean "at-a-level-so-high-that-nobody-currently-knows", but merely "very-high-level".
With this in mind, what does "open-ended" mean here on Cross-Validated, in the context of "research-level" questions?