Hi cvwoo
Well, the bat number is used for products, in our case for each inventory.
If you activate this feature, in purchase orders screen you will be able to search by batch number, so all the POs which contains this number will be displayed.
Also, you can filter by batch number in Stock Central.
This is how it works. Please, let me know if you need anything else as I am not sure if I have answered your questions. If this is the case, please, try to explain it more widely.
Best Regards,
Andrea.