This function returns the index of the raster image named gr_name for the HDF GR interface identified by the parameter gr_id.
            The value of index can be passed into HDF_GR_SELECT to obtain the raster image identifier (ri_id).
            Syntax
            Result = HDF_GR_NAMETOINDEX(gr_id, gr_name)
            Return Value
            Returns the index of the raster image if successful or FAIL (-1) otherwise.
            Arguments
            gr_id
            HDF_GR_ interface identifier returned by HDF_GR_START.
            gr_name
            Name of the raster image.
            Keywords
            None 
            Version History