Often, ‘UDI medium’ is commonly abbreviated to ‘UDI code’ for the sake of simplicity, especially when referring to the code itself printed or represented (either in readable or scannable form).

However, technically:

• UDI carrier means the physical medium or format (e.g. label, direct marking, barcode, RFID, etc.) on which the UDI code is represented.
• UDI code is the data sequence that uniquely identifies the device.