How to join Journal Entries to Journal Voucher Transactions

My understanding is that there should be a direct relationship between a Journal Voucher transaction row (OBTF) and the Journal Entry (OJDT) created when you post the voucher.

• OJDT stores a reference to OBTF.BatchNum, but does not appear to store a reference to OBTF.TransId, the second part of OBTFs primary Key.
• OBTF does not appear to store a reference to OJDT.TransID, that table's primary key.

Are these two tables meant to be directly related? If so, how can they be reliably joined?

Thanks in advance for your help.

-paul