Alternate SKUs are very important for managing inventory when selling across multiple sales channels. It allows the user to map different product identifiers to the same product to ensure inventory deductions are accurate. Some common alternate SKUs include the following:
ASIN
FNSKU
Any other auto generated SKU that defers from your default identifier
Note - A UPC is not considered an alternate SKU in Luminous. UPC's are included in their own field.
Here's a bit more information about how to manage alternate SKUs and why they're important: