Into what form does the barcode reader convert individual bar patterns?

Numbers and/or letters (binary digits)

A barcode reader captures and translates the barcode into numbers and/or letters and then sends this data to a computer so that it can make sense of the data. Basically, when the reader moves past the barcode, the light on the scanner generates a pattern of on-off pulses that corresponds to the barcodes (black and white stripes). The scanner then converts these on and off pulses into binary digits and then sends them to a computer.

when listing items that have an order of priority.