Microsoft DOS sample
The DOSCL application is a Generic Card Services client operating under DOS. During Instance Initialization, DOSCL checks if the Card Services interface is installed. If yes, DOSCL registers the Card Services client; the callback interface dispatches Card Services notifications. The interface distinguishes between notifications and requests. Notifications notify the client about specific events. Requests require the answer from the client. DOSCL puts event parameters string on the STDOUT device. You have to rewrite the dispatcher in order to match your specific requirements. DOSCL stays in monitor mode until a key is pressed.