All GeoStan functions use a common internal data structure you initialize with a call to the initialization function. This function returns an ID, which GeoStan passes to every other GeoStan function. Upon completion of the geocoding session, a call to the termination function frees the memory allocated by the initialization function and closes all files used by GeoStan.
Each GeoStan function returns either a status code or a pointer. There is a symbolic constant for every status code returned by a function. If the function returns a pointer, there is usually only one possible error indicated by the return of NULL. See the individual language chapters for possible status codes for each function.