This structure defines the metadata of the expression operands, including arguments passed to the function and the return type.
The structure contains the following metadata:
datatype.
Datatype of the argument.
precision.
Precision of the argument.
scale.
Scale of the argument.
isValueConstant.
Indicates if the argument is a constant. If so, the framework evaluates the argument once for each function call. The framework uses isValueConstant to optimize for performance. For input arguments that are constants, the plug-in can get the argument values during function instance initialization to optimize performance. For output values, the plug-in sets isValueConstant to TRUE.