Physiographic designation
Broader class
(1/9)  Common auxiliaries of place. Table 1e
Narrower classes
(21)Surface of the Earth in general. Land areas in particular. Natural zones and regions
(23)Above sea level. Surface relief. Above ground generally. Mountains
(24)Below sea level. Underground. Subterranean
(25)Natural flat ground (at, above or below sea level). The ground in its natural condition, cultivated or inhabited
(26)Oceans, seas and interconnections
(28)Inland waters
(29)The world according to physiographic features