The definition of an argument does not seem to cover many assumed use cases, and we believe that is not intentional. There should be answers to questions such as: Are lambda-captures arguments? Are type names in a throw-spec arguments? “Argument” to casts, typeid, alignof, alignas, decltype and sizeof? why in x[arg] arg is not an argument, but the value forwarded to operator[]() is? Does not apply to operators as call-points not bounded by parentheses? Similar for copy initialization and conversion? What are deduced template “arguments?” what are “default arguments?” can attributes have arguments? What about concepts, requires clauses and concept_map instantiations? What about user-defined literals where parens are not used?