You can print POS receipts for your orders in Zenstores in much the same way as generating invoices. 

What does the barcode do?
The barcode on POS receipts store the order number of the order. 

1. Select all the orders you want to print POS receipts for.

2. The click the Print button and select Print POS receipt from the dropdown.

3. Then select your preferred POS receipt label size and click the Generate PDF button.

4. This will then generate a PDF similar to the one below.

At the top you will see there is a barcode, when this is scanned it will display the order number for the order.
Then below this there is a small invoice, detailing the contents of the order.