All DLN API functions use the DLN_RESULT type for return values. The DLN_RESULT type and return codes are defined in dln_result.h file.
The DLN_RESULT values are divided into three types: success values, warnings and error values.
When testing a return value, you could use one of the following macros (they are also defined in dln_result.h file):
DLN_SUCCEEDED(Result)
Evaluates to TRUE if the Result value is a success type (0 – 0x1F) or a warning type (0x20 – 0x3F).
DLN_WARNING(Result)
Evaluates to TRUE if the Result value is a warning type (0x20 – 0x3F).
DLN_FAILED(Result)
Evaluates to TRUE if the Result value is an error type (greater than 0x40).