The STATUS Argument and Error Reporting

All TRANSFORM routines carry a final integer STATUS argument and adhere to the ADAM inherited error handling strategy. Unless otherwise indicated, a routine which finds that STATUS is not set to SAI__OK¹¹on entry will assume an error has occurred in a previous routine and will return immediately without action and without accessing other arguments (which may not be defined under error conditions). The value of the STATUS argument will not be changed. This behaviour usually allows tests of the STATUS value to be deferred until after several routine calls have been made.

If a TRANSFORM routine is called with STATUS set to SAI__OK, then it will attempt to execute. If it subsequently encounters an error, it will first perform any ``cleaning up'' which is possible and will then exit with its STATUS argument set to one of the error codes described in the next Section. When a STATUS value is set by a TRANSFORM routine, an associated error report will always be made by calling the ERR routine ERR_REP. The report will normally contain additional information about the circumstances of the error. Transmission of the report to the user will be deferred by the ERR facility pending action by the caller of the TRANSFORM routine (such as a call to ERR_FLUSH to output the error, or ERR_ANNUL to ignore it). The documentation for the ERR facility should be consulted for further details.