Barcode zone.

A block on the back cover where the printer's barcode goes or where a supplied barcode must sit. IngramSpark makes barcodes mandatory on the back of every cover, 100% black on a white box or background, places one if the file has none, and asks for a 1.75 x 1 in area left free. KDP's hardcover page says a barcode you supply must be 2 in (50.8 mm) wide and 1.2 in (30.5 mm) high at 300 dpi, at least 0.76 in (19 mm) from the bottom of the cover and at least 0.25 in (6 mm) from the spine hinge; if you supply none, KDP puts its own in a white box of that size at the lower right of the back cover and prints over anything beneath it. KDP's paperback page shows a barcode margin in its template, says it keeps the barcode from shifting during printing so that it scans, and also places a barcode when the file has none. The two platforms give different sizes, 1.75 x 1 in against 2 x 1.2 in. Anything important inside the zone is covered, so keep text and art out of it, as with the safe area.