Does your business have multiple outlets? Setting the prefix invoice number per outlet will certainly help you to distinguish the invoice code/sales transaction based on the outlet you have. For detailed steps you can check the following article:
Step 1. Go to Setup - More Menu - Application
Step 2. Transaction Numbering Tab - Setting Outlet Code for Invoice - Save
Step 3. Go to Outlets - Select & Edit Any Outlet
Click one of the outlets that you want to choose.
Step 4. Try to Make Sales Transaction to View the Result
Recheck invoice number.
[Tutorial Video] Assign Outlet Code for Invoice Number Prefix
You might also like to read this article :
To setup transaction numbering, check this article Setup Transaction Numbering
To add a prefix to the transaction number : Adding Prefix for Transaction Number
If the default invoice format used is not suitable for your business needs, we have several format options provided, check this article : Invoice Numbering Options Format