locale(const locale& other, const char* std_name, category);

has

Throws: runtime_error if the argument is not valid, or is null.

There being three arguments, the statement is rather problematic.

It looks like a copy/paste from

explicit locale(const char* std_name);

The conclusion seems to be that the statement should be changed to read:

Throws: runtime_error if std_name is not valid, or is null.