Scan some barcodes with your (non-declawed) CueCat.

When you scan a book with an ISBN barcode, you'll see it in the ISBN field.

When you scan, say, a Coke can, or a box of crackers, you'll see the barcode in the UPC-A field.

If you scan something else, like a pack of gum (it's smaller so it has a different kind of barcode), or a box sent via UPS (that tracking number is in a 'Code 128' barcode) it'll show up in the 'Anything else'+ box.