Source Transaction
Any business transaction that you, the user, create (including sale invoices, vendor bills, purchase orders, or checks) which are automatically posted as you work into the General Ledger Audit Trail. This is to distinguish these transactions from the G/L transactions automatically generated from them.
The Source Transaction ID in the G/L Audit Trail always refers to the Transaction ID of the Source Transaction and is separate from the G/L Transaction ID. (In other words, the Transaction ID of a particular G/L Transaction is almost always different from the Transaction ID of the Source from which it was created.)
Entries made manually into the G/L have no Source Transaction ID.