status.i4.v = sr_read_snapshot_c(device_index.i4.v, property.i4.v,
					 file_number.i4.v, snapshot_mode.i4.r,
					 timestamps.r8a.r, values.r8a.r,
					 num_values.u4.r [,units_text.i1a.r]
					 [,data_source.i4.v] [,case_number.i4.v]
					 [,user_id.i4.v] [,sda_usage.i1a.r]

	This routine returns snapshot data that has been previously saved by
	the save/restore system.

	device_index	device index
	property	property index (constants are in dbprops)
	file_number	file number from which to retrieve data
			(This is the subsystem number or user key 1 for
			 detached snapshot manager data.)
	snapshot_mode	returned snapshot data acquisiton mode
			(DIO_STANDARD_SNAPSHOT_MODE -> data was acquired
			 following arm event and delay,
			 DIO_TRANSIENT_RECORDER_MODE -> data was acquired
			 constantly until "reference_point" points after the
			 arm event)
	reference_point	returned reference point which depends on the
			snapshot data acquisition mode
			(DIO_STANDARD_SNAPSHOT_MODE -> snapshot delay value
						       in 100 microsecond units,
			 DIO_TRANSIENT_RECORDER_MODE -> index into data array
							where triggering event
							occurred (starts at 0))
	timestamps	returned array of timestamps which depend on the
			data acquisition mode (units are 100 microseconds)
			(DIO_STANDARD_SNAPSHOT_MODE -> delta timestamps from
						       the trigger and delay,
			 DIO_TRANSIENT_RECORDER_MODE -> delta timestamps from
							the first point)
	values		returned array of snapshot values
	num_values	number of values returned
	[units_text]	returned units text (LEN_DEV_UNITS characters)
			(default is NULL)
	[data_source]	source of data
			(SRMNGR_SDA_DATA -> SDA data (default),
			 SRMNGR_SNAP_DATA -> detached snapshot manager data)
	[case_number]	SDA case number (This is the record number or
			user key 2 for detached snapshot data.)
			 for SDA data and 0 for detached snapshot data)
	[user_id]	user ID or SDA subcase (This is user ID for detached
			snapshot manager data or the subcase number for
			SDA data.)  (default (CLIB_DEFAULT_ARG) is
			0 for detached snapshot manager data)
	[sda_usage]	null terminated SDA usage string (This argument only
			has meaning if the data source is SDA.)
			(default is NULL which results in Collider shot access)
	[options]	retrieval options
			(SRMNGR_OPT_NONE -> not options selected (default),
			 SRMNGR_OPT_INTERPOLATE_TIMES -> interpolate between
							 matching timestamps)

	This function returns ACNET status values as follows:

	OK			success
	DIO_BADARG		invalid data source
	DIO_INVDATA		no snapshot data points were taken
	DIO_MEMFAIL		memory allocation failure
	negative value		other ACNET format error

	This function requires the following include files:

	cnsparam_h, dbprops_h, cbslib_h, acnet_errors_h

	Related functions:

	sr_get_snapshot_c, sr_set_source_c, sr_sda_snapshot_stats_c,
	sr_snapshot_header_c, sr_snapshot_info_c, sr_snapshot_info_list_c,
	sr_get_device_c, sr_get_device_raw_c, sr_snap_directory_info_c,
	sr_snap_date_to_file_info_c, sr_snap_active_devices_c, sr_disconnect,
	sr_sda_cases_present_c, sr_sda_num_subcases_c,
	sr_sda_subcases_present_c, sr_sda_case_times_c

	C/C++ usage:

	char	units_text[LEN_DEV_UNITS];
	char	sda_usage = (char *) NULL;
	int	status;
	int	device_index = 27235;
	int	property = PRREAD;
	int	file_number = 0;
	int	snapshot_mode;
	int	num_values;
	int	data_source = SRMNGR_NORMAL;
	int	case_number = SDA_DEFAULT_CASE_NUMBER;
	int	subcase_num = SDA_DEFAULT_SUBCASE_NUMBER;
	unsigned int	options = SRMNGR_OPT_NONE;
	double	reference_point;
	double	timestamps[SRMNGR_MAX_SNAPSHOT_POINTS];

	status = sr_read_snapshot_c(device_index,property,file_number,