cal	OUT:	Calibration factor
	cal_err	OUT:	Calibration error
	offset	OUT:	Uncalibrated offset
	offset_err	OUT:	Uncalibrated offset error
	data_type	OUT:	Data type of uncalibrated data

	Purpose	Retrieves the calibration record, if there is one, attached to a scientific dataset.
	Return value	Returns SUCCEED (or 0) if successful and FAIL (or -1) otherwise.
	Description	A calibration record contains four 64-bit floating point values followed by a 32-bit integer.
		The relationship between a value iy stored in a dataset and the actual value y is defined as:
		y = cal * (iy - offset)
		The variable offset_err contains a potential error of offset, and cal_err contains a potential error of cal. Currently the calibration record is provided for information only. The SD interface performs no operations on the data based on the calibration tag.
		As an example, suppose the values in the calibrated dataset iy[] are the following integers:
		iy[6] = {2, 4, 5, 11, 26, 81}
		By defining cal = 0.50 and offset = -200.0 and applying the calibration formula, the calibrated dataset iy[] returns to its original form as a floating point array:
		y[6] = {1001.0, 1002.0, 1002.5, 1005.5, 1013.0,1040.5}

	FORTRAN	integer function dsgcal(cal, cal_err, offset, offset_err, data_type)
		real cal, cal_err, offset, offset_err
		integer data_type