sds_id	IN:	Data set identifier returned by SDcreate or SDselect
	fill_value	IN:	Fill value

	Purpose	Sets the fill value for a data set.
	Return value	Returns SUCCEED (or 0) if successful and FAIL (or -1) otherwise.
	Description	SDsetfillvalue sets the fill value specified by the fill_value parameter for the data set identified by the sds_id parameter.
		The fill value is assumed to have the same data type as the data set.
		It is recommended to call SDsetfillvalue before writing data.

	FORTRAN	integer function sfsfill(sds_id, fill_value)
		integer sds_id
		<valid numeric data type> fill_value
		integer function sfscfill(sds_id, fill_value)
		integer sds_id
		character*(*) fill_value