In telecommunication, a machine-readable medium (automated data medium) is a medium capable of storing data in a form that can be accessed by an automated sensing device.

Examples of machine-readable media include (a) magnetic diskss, cards, tapes, and drums, (b) punched cards and paper tapes, (c) optical disks, (d) barcodes and (e) magnetic ink characters.

Original source: Federal Standard 1037C