Cube View Parametric driven column

For cube views, you could write an XFBR to derive the prior forecast based on the forecast that was selected via parameter.  For quick views, I would recommend setting up some literal parameters.  This would be something the admin would maintain, but it's very easy and only a once a month update.

Example of how you could setup these literal parameters:

|!CurrFcstScenario!| = Feb_FCST

|!PriorFcstScenario!| = Jan_FCST 

Then you teach the users how to use the above two literal value parameters in their quick views and XFGetCell's to automate the correct forecast scenarios.  

I agree with aricgresko on perhaps using an XFBR business rule. The below code could be optimized in many ways, but should work for what you need. This way you do not need to use/manage any text values.

"YourRuleNameHere" will equal what you named your XFBR business rule, ensure whatever you named it matches the XFBR call you place in the cube view.

XFBR Cube View Line Call (What you would put on your cube view line instead of "S#|!param_FCST!|"):

XFBR(YourRuleNameHere, GetPriorFcst, CurrentFcst=|!param_FCST!|)

Create an XFBR Business Rule and paste in the following code:

Imports System
Imports System.Data
Imports System.Data.Common
Imports System.IO
Imports System.Collections.Generic
Imports System.Globalization
Imports System.Linq
Imports Microsoft.VisualBasic
Imports System.Windows.Forms
Imports OneStream.Shared.Common
Imports OneStream.Shared.Wcf
Imports OneStream.Shared.Engine
Imports OneStream.Shared.Database
Imports OneStream.Stage.Engine
Imports OneStream.Stage.Database
Imports OneStream.Finance.Engine
Imports OneStream.Finance.Database

Namespace OneStream.BusinessRule.DashboardStringFunction.YourRuleNameHere   '<--------- NEED TO CHANGE "YourRuleNameHere" AND ADD TO XFBR CALL WITHIN CUBE VIEW
	Public Class MainClass
		Public Function Main(ByVal si As SessionInfo, ByVal globals As BRGlobals, ByVal api As Object, ByVal args As DashboardStringFunctionArgs) As Object
			Try
				If args.FunctionName.XFEqualsIgnoreCase("GetPriorFcst") Then
						Dim CurrFcst As String = args.NameValuePairs("CurrentFcst")
				   	    Dim PriorFcst As String = String.Empty
					
						Select Case CurrFcst
							Case "Jan_FCST"
								PriorFcst = "Dec_FCST"
							Case "Feb_FCST"
								PriorFcst = "Jan_FCST"
							Case "Mar_FCST"
								PriorFcst = "Feb_FCST"
							Case "Apr_FCST"
								PriorFcst = "Mar_FCST"
							Case "May_FCST"
								PriorFcst = "Apr_FCST"
							Case "Jun_FCST"
								PriorFcst = "May_FCST"
							Case "Jul_FCST"
								PriorFcst = "Jun_FCST"
							Case "Aug_FCST"
								PriorFcst = "Jul_FCST"
							Case "Sep_FCST"
								PriorFcst = "Aug_FCST"
							Case "Oct_FCST"
								PriorFcst = "Sep_FCST"
							Case "Nov_FCST"
								PriorFcst = "Oct_FCST"
							Case "Dec_FCST"
								PriorFcst = "Nov_FCST"						
						End Select

					Return "S#" & PriorFcst

				End If

				Return Nothing
			Catch ex As Exception
				Throw ErrorHandler.LogWrite(si, New XFException(si, ex))
			End Try
		End Function
	End Class
End Namespace

You could simplify this by having your column CY use T#|!CVQTR!| and your column PY use T#PeriodPrior4(|!CVQTR!|).  No need for an XFBR