In this FICO configuration activity we are able to define valuation methods for periodic processing of open items.
IMG Path: Financial Accounting (New) -> General Ledger Accounting (New) -> Periodic Processing -> Valuate -> Define Valuation Methods
Tables: T044A, T044B, T044AB, T044ABT
On the first screen you will be able to see a list of valuation methods defined in the system.
In detailed view after double click you will see following screen.
If you want to maintain time-dependent attributes you could do it here with following options.