# Define Calculations - the Period Definition Tab

Complete the following steps to create a period
definition.

## Procedure

- On the Reports menu, select Define Calculations. The Define Calculations window opens. The Account Definition tab is open.
- Open the Period Definition tab.
- In the Variable column, enter the period variable code, for example, P12. You can enter the same variable code several times if you want to retrieve values from several periods.
- In the Actuality column, select the actuality to retrieve values for and then enter the sign to multiply that value with in the Sign column.
- Enter the period formula to determine which period to retrieve
values from. For example, you can enter values according to the following
for the variable P12 in order to retrieve a rolling 12 month calculation:
Table 1. Example of period formula values Sign +/- Formula + +0 - -12 + N112 - Select the Average column to retrieve the average value for a period interval, that is, (OB+CB)/2.
- Click Save and open the Calculation Definitions tab.