virtual const char* name() const noexcept = 0;
Returns: A string naming the error category.
virtual error_condition default_error_condition(int ev) const noexcept;
Returns: An object of type error_condition that corresponds to ev.
virtual bool equivalent(int code, const error_condition& condition) const noexcept;
Returns: true if, for the category of error represented by *this, code is considered equivalent to condition; otherwise, false.
virtual bool equivalent(const error_code& code, int condition) const noexcept;
Returns: true if, for the category of error represented by *this, code is considered equivalent to condition; otherwise, false.