decimal_point - LC_NUMERIC cultural data item or locale definition file keyword representing the character that shall be used as the decimal delimiter in numeric, nonmonetary formatted quantities.

thousands_sep - LC_NUMERIC cultural data item or locale definition file keyword representing the string that shall be used as separator for groups of digits to the left of the decimal delimiter in numeric, nonmonetary formatted quantities.

grouping - LC_NUMERIC cultural data item or locale definition file keyword representing the sequence of integers separated by semicolons which define the sizes of each group of digits in formatted numeric, nonmonetary quantities. Grouping will only be performed for groups with a defined size, unless the last integer is zero, in which case the size of the last group will be repeatedly used for the remainder of the digits. The initial integer defines the size of the group immediately preceding the decimal delimiter, and the following integers define the preceding groups.