pattern do_neg_format() const;
The protected virtual member function returns a locale-specific rule for determining how to generate a monetary output
field for a negative amount. Each of the four elements of pattern::field can have the values:
none to match zero or more spaces or generate nothingsign to match or generate a positive or negative signspace to match zero or more spaces or generate a spacesymbol to match or generate a currency symbolvalue to match or generate a monetary valueComponents of a monetary output field are generated (and components of a monetary input field are matched) in the
order in which these elements appear in pattern::field. Each of the values sign, symbol, value, and either none
or space must appear exactly once. The value none must not appear first. The value space must not appear first or
last. If Intl is true, the order is symbol, sign, none, then value.
The template version of moneypunct<E, Intl> returns {money_base::symbol, money_base::sign,
money_base::value, money_base::none}.