To add to what @by_caballero said, though from an IETF perspective, it is not unusual for IETF to split “a specification” into a bunch of different documents, which include the following topics and may even have one document per topic:
- Problem statement: this is why we’re doing this.
- Use cases: current and envisioned use cases.
- Gap analysis/requirements: derived from use cases, what does AP currently offer or not offer.
- Architecture: with this high-level approach we think we can meet the requirements.
- Core specs: the main specifications, which reference the above.
- Extension specs: any additional things that aren’t really part of the core.
I have Thoughts ™ on how many core specs are necessary, but that’s not the main point. The main point is that a WG charter can easily encompass writing a single doc on each those points, with the last two most likely warranting several docs each.
That also means that the WG charter can be written so that these topics are covered.
(W3C works a bit differently and I have less experience there, so YMMV on the above. It’s more the topic-based approach that I’m advocating for here.)