@pclaud0910  RE: How are GL account numbers assigned to a transaction outside of line items and receivable, payable, bank.

You assign the accounts. They can be assigned directly on purchases and expense transactions like bills, credit cards charges, and checks, or indirectly using items, for most all transaction types.

For inventory items and sales three accounts are used, the accounts set up on the inventory item. Usually on purchases only the inventory account is used.