[dcl.stc] p3 "It shall be applied only to the names of variables of namespace or block scope and to the names of static data members."
(Note "shall", "and", "names")

[dcl.stc] p5 "The extern specifier can be applied only to the names of variables and functions."
(Note "can", "and", "names")

[dcl.constexpr] p1 "The constexpr specifier shall be applied only to the definition of a variable or variable template or the declaration of a function or function template."
(Note "shall", "or", "definition/declaration")

[dcl.inline] p1 "The inline specifier can be applied only to the declaration or definition of a variable or function."
(Note "can", "or", "declaration or definition")

We should clean up the mess. Suggestion: use "shall", "or" ,and "declaration" / "definition" as appropriate (but only one of them), plus use singular.