Ensure that all pending error
messages in the current error context have been output to the user. On successful completion, the error
context is annulled and STATUS reset to SAI__OK
If no error messages have been reported in the current error context, a warning message is generated
but no error results.
If an error occurs during output of the error messages, the error context is not annulled and STATUS is
returned set to ERR__OPTER.
CALL ERR_FLUSH( STATUS )
The global status: it is set to SAI__OK on return if the error message output is
successful; if not, it is set to ERR__OPTER.