The term constexpr iterator is defined in [iterator.requirements.general] as follows:

-16- Iterators are called constexpr iterators if all operations provided to meet iterator category
requirements are constexpr functions.

[Note 3: For example, the types "pointer to int" and reverse_iterator<int*> are constexpr iterators. - end note]

The particular form of this definition using the term "called" is untypical for introducing a requirement and has let to the interpretation in the proposed wording of LWG 4038 that when we require a type to meet the requirement of a constexpr iterator we should impose an "is a constexpr iterator" requirement.

This deviates from all existing places where we impose the form "meets the constexpr iterator requirements" instead ([string.view.iterators] p1, [basic.string.general] p5, [container.opt.reqmts] p1, [array.overview] p5, [vector.overview] p3).

Note that the term "meets the XX requirements" is not restricted to the Cpp17YY requirements, we use it elsewhere too, e.g. when we say that a type meets the character traits requirements ([char.traits]), the allocator-aware container requirements ([container.alloc.reqmts), or the layout mappings requirements ([mdspan.layout.policy.reqmts]), so this change would not be conflicting with existing style forms.

To make the status quo clearer this issue suggests to reword [iterator.requirements.general] to be a requirement. The alternative would be to change all currently referencing places to say "is a constexpr iterator" instead. Personally I prefer the notion of "meets the XX requirements" in this case.