The ExpiryMonth of the frame.
An integer representing the number corresponding to the month the card expires.
Obtaining good results for the ExpiryMonth and ExpiryYear sometimes requires many frames. Scanning can continue (even after the ScanFrameStatus is NumbersFound), as long as ExpiryMonth and ExpiryYear are equal to 0. The input may be a zero-filled two-digit number, but the output will be the actual month number.