typedef long CTL_STATUS_t;
CTL_STATUS_t is the new status code mechanism for the add-on libraries, such as the mass storage library, TCP/IP networking library, USB device library, sensor library, and the set of drivers associated with them.
All error codes indicating errors are negative. A zero indicates a "no error" condition. API calls may return zero to indicate success if they only need to indicate success or failure. API calls may wish to return more information, which is always positive.