052 GEOGRAPHIC CLASSIFICATION CODE (R)Indicators First Code source ^ Library of Congress Classfication 1 U.S. Dept. of Defense Classification 0 U.S. Dept. of Defense Classification [OBSOLETE] 7 Source specified in subfield $2 Second indicator is undefined; contains a blank (^)Subfield Codes $a Geographic classification area code (NR) $b Geographic classification subarea code (R) $c Populated place name (R) $2 Code source (NR) $6 Linkage (NR) $8 Field link and sequence number (R)