[allocator.requirements.general] The meaning of "parameterized in terms of allocators" seems unclear

[allocator.requirements.general]/1 says

All of the string types, containers (except array), string buffers and string streams ([input.output]), and match_results are parameterized in terms of allocators.

It's not very clear for me whether this sentence imposes some normative requirements, or if it does, what the requirements are, and [syncstream] is not yet covered.

Perhaps it means

If any template in [strings], [containers], [input.output], or [re] is instantiated and any template parameter named Allocator, Alloc, or SAlloc is substituted with a type that does not meet the Cpp17Allocator requirements, the behavior is undefined.

Not sure whether an LWG issue is needed.

Start with [allocator.requirements.general]/1 and compare the listed library components with [syncstream]. Review the comment discussion and determine whether the sentence imposes normative requirements or needs clearer wording. Done means the allocator relationship and scope are unambiguous, including whether syncstream is covered.