status.i4.v = dio_dev_ssdn(device_indices.i4a.r, properties.i2a.r,
				   ssdns.i1a.r, errors.i2a.r

	status.i4.v = dio_dev_ssdn_c(device_indices.i4a.r, properties.i2a.r,
				     ssdns.i1a.r, errors.i2a.r

	This routine returns the SubSystem Device Number (SSDN) info for
	a device and property (DI/PI).  If "num_devices" is specified, SSDNs
	for a list of devices/properties can be retrieved.

	device_indices	device index or array of device indices
	properties	property index or array of indices
			(If the first value is less than zero, all devices
			 will be requested with a property index which is
			 equal to the absolute value of this argument.)
			(constants are in 'dbprops')
	ssdns		returned SSDN data (LEN_SSDN bytes per device)
			(A value of NULL may be passed if no SSDN data
			 is needed.)
	errors		returned ACNET status value or array of status values
	[num_devices]	number of devices (default is 1)

	This function returns status values as follows:

	OK			success
	DIO_BADARG		invalid number of devices passed
	DIO_MEMFAIL		memory allocation failure
	negative value		ACNET format error indicating overall failure
	positive value		number of devices in error indicating partial

	This function requires the following include files:

	dbprops_h, cnsparam_h, diolib_h, acnet_errors_h

	Related functions:

	dio_get_properties, dio_dev_type, dio_device_location_c,
	dio_dpreq_info, dio_cache_property_info_c, error_in_list(_c),
	dio_enable_obsolete_dev_info, dio_disable_obsolete_dev_info

	C/C++ usage:

	char	ssdn[NUM_DEVICES][LEN_SSDN];
	short	errors[NUM_DEVICES];
	short	properties = -PRREAD;
	int	status;
	static const int	device_indices[NUM_DEVICES] = {14430, 14431};
	int	num_devices = NUM_DEVICES;

	status = dio_dev_ssdn_c(device_indices,&properties,(char *) ssdns,