Update of subvar OEP_PriorYr for All Cubes

Summary:

What triggers the automatic update of subvar OEP_PriorYr for All Cubes?

Content (please ensure you mask any confidential information):

We have got a Pipeline which uses STARTPERIOD and ENDPERIOD variables to point to subvar OEP_PriorYr and OEP_CurYr for All Cubes, which we believe are seeded substitution variables.

We use Config: Financials -> Planning and Forecast Prepartion to set Current Fiscal Year and Period. We can see that the update of the Current Fiscal Year would update subvar OEP_CurYr for All Cubes, but it would not update subvar OEP_PriorYr for All Cubes.

How does subvar OEP_PriorYr for All Cubes get updated?