The T1_DATA structure is used by the Smart Card Driver Library for processing T1 I/O. It should not be directly modified by a driver.
typedef struct _T1_DATA {
    //
    // Current information field size that can be transmitted
    //
    UCHAR    InfSize;
    //
    // Number of bytes already received from smart card
    // 
    ULONG    BytesReceived;
    //
    // Number of bytes already sent to the card;
    //
    ULONG    BytesSent;
    //
    // Total number of bytes still to send
    // 
    ULONG    BytesToSend;
    //
    // T1 error code of last received block
    //
    UCHAR    LastError;
    //
    // This is the node address byte to be sent to the card
    //
    UCHAR     NAD;
    //
    // State before error occurred
    //
    ULONG    PrevState;
    //
    // Resend counter
    //
    UCHAR    Resend;
    //
    // Resync counter
    //
    UCHAR    Resynch;
    //
    // The Send Sequence Number is either 0 or 1 as defined in ISO 7816-3
    //
    UCHAR    SSN;
    //
    // Current state of protocol
    //
    ULONG    State;
    //
    // Waiting time extension requested by the smart card
    // This value should be used by the driver to extend block waiting time.
    //
    UCHAR    Wtx;
} T1_DATA, *PT1_DATA;
 The following member is important for the driver: