sds_id	IN:	Data set identifier returned by SDcreate or SDselect
	dim_index	IN:	Index of the dimension

	Purpose	Returns the identifier of a dimension given its index.
	Return value	Returns the dimension identifier (dim_id) if successful and FAIL (or -1) otherwise.
	Description	SDgetdimid returns the identifier of the dimension specified by its index, the parameter dim_index.
		The dimension index is a nonnegative integer and is less than the total number of data set dimensions returned by SDgetinfo.

	FORTRAN	integer function sfdimid(sds_id, dim_index)
		integer sds_id, dim_index