sds_id	IN:	SDS identifier
	emptySDS	OUT:	Boolean value indicating whether the SDS is empty

	Purpose	Determines whether a scientific dataset (an SDS) is empty.
	Return value	Returns SUCCEED (or 0) if successful and FAIL (or -1) otherwise.
	Description	SDcheckempty sets the parameter emptySDS to TRUE if the dataset identified by sds_id has not been written with data, and to FALSE, otherwise.
		The Fortran routine, sfchempty, returns 1 in emptySDS if the dataset is empty and 0 otherwise.

	FORTRAN	integer function sfchempty(sds_id, emptySDS)
		integer sds_id, emptySDS