KSEC1 element	Contents	GRIB octet	Recommended GRIB_API keys	Coded GRIB_API keys	Comments
37	ECMWF local GRIB use definition identifier. 20 = 4D variational increments	41	localDefinitionNumber	localDefinitionNumber
38	Class	42	class	marsClass
39	Type =33(4D variational increments)	43	type	marsType
40	Stream	44-45	stream	marsStream
41	Version number or experiment identifier. (4 ASCII characters, right justified)	46-49	expver	experimentVersionNumber
42	Iteration	50	iteration	marsIteration
43	Total number of iterations	51	totalNumberOfIterations	totalNumberOfIterations
-	Spare (set to zero).	52