Name	Notation	Description	Types	Status
On direct sun	0		Concept	stable
On direct moon	1		Concept	stable
On blue zenith sky	2		Concept	stable
On zenith cloud (uniform stratified layer of small opacity)	3		Concept	stable
On zenith cloud (uniform or moderately variable layer of medium opacity)	4		Concept	stable
On zenith cloud (uniform or moderately variable layer of large opacity)	5		Concept	stable
On zenith cloud (highly variable opacity, with or without precipitation)	6		Concept	stable
On zenith cloud (fog)	7		Concept	stable
On zenith haze	8		Concept	stable
On direct sun through thin cloud, fog or haze	9		Concept	stable
Missing value	15		Concept	stable