status.i4.v = dio_device_has_expression_c(device_indices.i4a.r,

	This routine determines if there is an expression which is used
	to calculate a device reading.

	device_indices	device index or array of device indices
	has_expression	returned logical value or array of logical values
			(TRUE -> device has a defined expression,
			 FALSE -> device does not have a defined expression)
	errors		returned ACNET status value or array of status values
	[num_devices]	number of devices

	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:

	diolib_h, acnet_errors_h

	Related functions:

	dio_device_expression_c, error_in_list(_c)

	C/C++ usage:

	short	errors[NUM_DEVICES];
	int	status;
	static const int	device_indices[NUM_DEVICES] = {14430, 14431};
	int	has_expr[NUM_DEVICES];
	int	num_devices = NUM_DEVICES;

	status = dio_device_has_expression_c(device_indices,has_expr,