Discontinued codes are identified by a hyphen preceding the first letter in the code string.

x

Earth

xa

Eastern Hemisphere

xb

Northern Hemisphere

xc

Southern Hemisphere

xd

Western Hemisphere

 

NOTE:  The GAC for Earth ( x ) is only assigned if the subject heading Earth by itself or with subdivisions (Earth--Crust; Earth--Density; Earth--Mantle) is assigned.  It is not used for topics (like Meteorology, Geology, etc.) which are earth-centric but in which the location of the earth is taken for granted.

See also:

Geographic Area Code Sequence