If you have started creating an invoice for one customer but need to pause and assist another, Orchid POS will automatically save any item in the customer's open cart.
This means you do not have to do anything special to save the invoice you are building. Simply click CHANGE CUSTOMER to bring up another customer, and when you are ready to bring up the original, all items will still be on their invoice.
If you need to search open carts, you can do so from the Run Tab menu in Point of Sale, then Open Tab/Carts. Click from "View Tabs" to "Open Carts.
Running Tabs:
Saving an open cart as a running tab will keep the invoice intact, but move it off of the customer's invoice screen in Point of Sale to be recalled later. You cannot save an invoice with deposit or A/R payment line items to running tab.
Compile the cart in Point of Sale then select RUN TAB menu > Run Tab