This document provides instructions for specifying open posting periods in SAP for cost center accounting. It describes how to use transaction code S_ALR_87003642 to set time intervals for posting and account number ranges. For example, at month end, a user can close customer and vendor accounts for posting but keep general ledger accounts open using this transaction. The steps show how to allow postings for July and August 2002 for all account types by entering the from and to periods in the specified transaction code.