All HEPDB routines have an integer return code IRC as last argument. If, on return, this contains the value zero then the routine was successful. A non-zero return code indicates an error. The error codes may be translated to a meaningful error message using the routine CDERR. An explicit message is printed out when the debug log level has been set to 1 or a higher value, through a call to CDLOGL (the debug level is set by default to 0 in CDOPEN).
Some routines return additional status information in the Zebra common block /QUEST/IQUEST(100). However, the user is not required to test on the values of the IQUEST vector on return.