This function calculates the difference between the value of the current period and the opening value. (Current - Opening)
The opening value will be derived differently based on the View parameter passed to the function.
If the View parameter is "YTD", the opening value will be retrieved from the last period of the prior year.
If the View parameter is "Periodic", the opening value will be retrieved from the prior period of the current year. If the current period is the first period of the year, the opening value will be retrieved from the last period of the prior year.
If the View parameter is blank ( " " ), the opening value will be based upon the default data view of the scenario.