PARAMis the returned message name and
PARLENthe length of the message name.
OPSTRis the returned error message text and
OPLENis the length of the error message in
OPSTR. If the message text is longer than the declared length of
OPSTR, then the message is truncated with an ellipsis, i.e. “…”, but no error results.
The status associated with the returned message is returned in
STATUS until there are no more
messages to return – then
STATUS is set to SAI__OK,
OPSTR are set to blanks and
OPLEN to 1. If there are no messages pending on the first call, a warning message is generated and
STATUS set to EMS__NOMSG
After STATUS has been returned SAI__OK, the whole process is repeated for subsequent calls.