Q:  What do errors like the following mean?

	DPS client library error while writing to connection DPS context c18c data -102

A:  The error reporter is basically printing out the elements of data passed in the exception initiated by NX_RAISE().  Usually the header file that defines the exception codes tells what data items are also passed.  Since this is a DPS client library error, we look through <dpsclient/dpsclient.h> for a write error exception code:

	dps_err_select, dps_err_read and dps_err_write signal communication
	errors in the connection.  The OS return code is passed in arg1;
	arg2 is unused.

In interpreting the dpsclient error message, the first data item is always the DPS context in which the error occurred.  The second item corresponds to arg1.  Note that any arg2 referred to in the exception code description doesn't get passed from the DPSErrorFunc into the NXRaise exception scheme.  Luckily, there aren't any DPS errors where arg2 is essential info.

So, for the above error, the c18c is a DPS context and the -102 is a Mach return code.  The Mach codes happen to be defined in <sys/message.h>.  By the way, negative numbers in about the -100 to -1000 range tend to be Mach error return codes.

QA492			

Valid for 1.0, 2.0, 3.0