JavaCard OS

I want to read and write javacard. What are the unique identifiers for javacard communication?

The unique identifiers for javacard communication? For typeA, the reader identifies cards by uid. For typeB, the reader identifies cards by pupi.
For T0 or T1, it is contact, no need to identify.

Maybe, you can descript your question in detail.

The unique identifier of javacard is ChipID.
And I think the reader ID is the unique identifier of javacard communication.