Name	Notation	Description	Types	Status
Observing rules for base of lowest cloud and cloud types of FM 12 SYNOP and FM 13 SHIP apply	0		Concept	stable
First non-Cumulonimbus significant layer	1		Concept	stable
Second non-Cumulonimbus significant layer	2		Concept	stable
Third non-Cumulonimbus significant layer	3		Concept	stable
Cumulonimbus layer	4		Concept	stable
Ceiling	5		Concept	stable
Clouds not detected below the following height(s)	6		Concept	stable
Low cloud	7		Concept	stable
Middle cloud	8		Concept	stable
High cloud	9		Concept	stable
Cloud layer with base below and top above the station	10		Concept	stable
Cloud layer with base and top below the station level	11		Concept	stable
No clouds detected by the cloud detection system	20		Concept	stable
First instrument detected cloud layer	21		Concept	stable
Second instrument detected cloud layer	22		Concept	stable
Third instrument detected cloud layer	23		Concept	stable
Fourth instrument detected cloud layer	24		Concept	stable
Value not applicable	62		Concept	stable
Missing value	63		Concept	stable