National Agricultural Library subject authority file:
Code d (008/11) indicates that the formulation of the 1XX heading conforms to the National Agricultural Library subject authority file that is maintained by the National Agricultural Library.
Examples:
008/11 d
150 ## $aCosmochemistry
008/11 d
008/10 c [code indicating AACR 2]
008/15 a [code indicating heading may be used as a subject added entry]
110 2# $aFarm Credit System (U.S.)