Whether errors lead to an abort or are handled by the program itself, is controlled via calls to STECNT.
There are several calls to the operating system via the OS interfaces within the MIDAS subroutines. Any error status encountered will force the execution of a system service exception handler, resulting in the display of various information on the user's terminal and abort of the application program. If the cause of this error is not obvious the error should be reported to the Image Processing Group at ESO, e.g. via the MIDAS command REPORT/PROBLEM) or, preferably, via the Feedback mechanism of the Motif based Graphical User Interface of the MIDAS Help (started via CREATE/GUI help in MIDAS).