As discussed on the mailing-list, it is proposed to develop a wrapper class around the double primitive type. This wrapper class should implement FieldElement. This would allow generic calculations on exchangeable number types (big fractions, big decimals, fractions, decimals). This class will be called Decimal64 (together with the corresponding Decimal64Field).
Similarly, to the BigReal class, the newly created Decimal64 class could go to the o.a.c.m3.util package.