TOPIC: Where is Acceptance criteria located?

A question regrading Acceptance criteria:

Where is Acceptance criteria located?
Is it in 'Requirement documentation' or 'WBS' .. I see contrasting answers in different reading materials.

I think that are in the scope statement which is output of the the define scope and this is because the acceptance criteria relate to the deliverables (which have to be accepted) and not to the requirements (which have to be fulfilled). Any other views out there?

Acceptance Criteria is in
5.3.3.1 Project Scope Statement
5.4.3.1 WBS Dictionary, more detailed and focusing on each specific work package

I don't think it's in the Requirements Documents. I performed a search in my electronic PMBOK.