DO_NOTHING Constant
You can use a DO_NOTHING constant in either a number or text calculation. When a calculation result is DO_NOTHING, the result field is not modified when that calculation is executed.
For example, Workflow State changes to closed when Closed is selected. If you do not want this field to change if this checkbox is cleared, you enter the following user-defined calculation:
WorkflowState = IfThenElse(Closed==1, “Closed”, @(DO_NOTHING))
The DO_NOTHING constant is a value of -9999. When -9999 is the value, the original value in the result field is not changed. You do not want to use the DO_NOTHING constant in the middle of a bigger function. In this case, either enter “” to indicate a blank text string or wrap the whole thing in an $IfThenElse() statement:
$IfThenElse( $ToNumber( [Incidents1.Closed]) = 1, "Status = Closed", @(DO_NOTHING))