Proposed resolution:

This wording is relative to N4713.

1. Edit [atomics.types.float] after p1, class template specialization atomic<floating-point> synopsis, as indicated:

     namespace std {
       template<> struct atomic<floating-point> {
         using value_type = floating-point;
         using difference_type = value_type;
         static constexpr bool is_always_lock_free = implementation-defined;
         […]
       };
     }
   

[ 2018-3-17 Adopted in Jacksonville ]

[ 2018-01-09 Moved to Tentatively Ready after 6 positive votes on c++std-lib. ]

The atomic<floating-point> specialization doesn't have the value_type and difference_type member typedefs, making it unusable with most of the nonmember function templates. This doesn't seem to be the intent.