Notation	Name	Description	Status
area	Area	a two-dimensional feature, either a plane, or some other surf...	stable
inapplicable	inapplicable	observing geometry inapplicable	stable
line	Line	a one-dimensional feature, either a straight line, or a curve...	stable
point	Point	a zero-dimensional feature	stable
totalColumn	Total column	the integral of the vertical distribution of a feature	stable
unknown	unknown	observing geometry unknown	stable
verticalProfile	Vertical profile	synonymous to vertical distribution of a feature	stable
volume	Volume	a three-dimensional feature	stable