The Basic UDI-DI is the main key in the database and relevant documentation (e.g. certificates, declaration of conformity, technical documentation and summary of safety and clinical performance) to connect devices with same intended purpose, risk class and essential design and manufacturing characteristics.
It is independent/separate from the packaging/labelling of the device and it does not appear on any trade item.
Any Basic UDI-DI shall identify the devices covered by that Basic UDI-DI in a unique manner
Source: Medical Device Coordination Group Document MDCG 2018-1 Rev. 4