The purpose of this report is mainly to allow the revaluation of foreign currency items in a companies AR and AP ledgers at the end of a financial period. If transactions of all currencies are included then logically all invoices and allocated payments are included therefore the total should equal the balance in the GL account. The report should produce two columns " this is value presently in the accounts" and "this is value that should be in the accounts if all the open trx in foreign currency were revalued to the exchange in the system on the date selected in the report parameters".
Another use of this report can be that if you have (say) multiple accounts receivable general ledger accounts then the open items report will not break up the the transactions by GL account code. This report does so it should provide a means to demonstrate that the open items agree with multiple AR control account balances.