This structure identifies a socket and function pair composed of a socket number and function number.
typedef struct {
UINT8 uSocket;
UINT8 uFunction;
} CARD_SOCKET_HANDLE, *PCARD_SOCKET_HANDLE;
The stream interface driver generates these values and uses them in various Card Services functions.
For single function cards, the function number is 0. For multiple function cards, the function number ranges from 0 through 1 less than the number of functions on the card.