...
If no target column is defined, the value of the expression (the input field Expression) will become the value of an eval tag. If is defined, it must contain the reference to a column of an object of Structured variable type in form: ObjectName[0]^ColumnName. This notation defines a structured variable column, which will contain the results of the expression evaluated.
ExampleNote:
If a constant expression of value 1 is defined, the process D2000 Calc (admistrator of objects of Eval tag) type ) ensures that all fields of a defined column will have the same value of 1.
...