The bClassGetResponse field is a number value from the USB CCID descriptor:
Significant only for CCID that offers an APDU level for exchanges.
Indicates the default class value used by the CCID when it sends a Get Response command to perform the transportation of an APDU by T=0 protocol.
Value FFh indicates that the CCID echoes the class of the APDU.
| bClassGetResponse | # | % |
|---|---|---|
| 0xFF | 151 | 59.45 % |
| 0x00 | 103 | 40.55 % |
The statistics here are the same as for the bClassEnvelope field.
All the readers have bClassEnvelope = bClassGetResponse set to either 0x00 or 0xFF.
It is not surprising to have bClassEnvelope = bClassGetResponse since the two fields are used to manage APDU (short or extended) with T=0 cards.