Expressions and  VB.NET™ scripts use the same syntax; the operators themselves are available in both environments, while the functions supported by the expressions constitute a reduced set of features available within the script. 

Expressions only allow the calculation of the final result of a  single-statement expression, that is self-contained within a single instruction line. Expression cannot be performs, for example, the instantiation or the assignment of variables, procedure calls, or conditional structures, displaying of dialog boxes, etc. ....


Important: Regardless of the locale of the system, Expressions requires a dot "." as decimal separator.