It's not that you didn't answer it correctly. I didn't ask it in a way that made sense to you. Here's an example from wikimedia. The content is not what would be appropriate for pg and it's more than a conceptual discussion, but you can I think see that several models are discussed for requirements in terms of the problem domain, not the solution technology. Similarly PG might have a document describing the problem/opportunity they intend to address, the nature of the population for whom they intend to address it, and how those people and PG describe ---- model --- organize the scope of what's being addressed, in terms that provide a common, accurate vocabulary. I'm still thinking how to say it. You began to address it, but I think it takes more time to fill out the scope and structure of it.