AGRICOLA -- Guide to Subject Indexing

No. 7, June 1986SUBJECT: Application of Hierarchies in the CAB ThesaurusDo not use a descriptor from the CAB Thesaurus unless the broader terms (the BTs) areconsistent with the meaning needed for the article you are indexing.• E.g., AGGREGATIONo BT1 statistical analysisDon't use the descriptor AGGREGATION outside the context of statistics. It is notavailable, for instance, for use with aggregations of insects or of cattle.• E.g., DRYINGo BT1 dehydration• BT2 processingDon't use the descriptor DRYING outside the context of human intervention in thedrying process. This is implied by the BT2 (PROCESSING). In cases such as thesetwo, search for a substitute descriptor in the Thesaurus, add some other term to field653, or consider whether the appearance of the term in the title may suffice.This instruction applies even if some of the related terms (rt's) do have meaningsconsistent with the meaning needed for the article you are indexing.• E.g., CABINSo BT1 boats and shipso rt holiday chaletsThe descriptor CABINS can only be used for the cabin of a boat/ship, not for a cabin inthe woods, despite the fact that the appearance of the rt HOLIDAY CHALETS leadsyou to believe that it might be. Other descriptors in this category include BEDDING,CHARGES, COMPRESSION, CROWN, and SUCCESSION.An obvious implication of these instructions is that an indexer should never use adescriptor based solely upon the fact that it appears as a related term of anotherdescriptor. Always check the full entry for the descriptor itself so that you can inspectits own hierarchy.EXCEPTIONS:Some descriptors (e.g., drugs and agrochemicals, crops) have been placed in hierarchieson the basis of their uses or applications. It is permissible to use one of these descriptorseven if the particular use to which it is being put in the article being indexed is notamong the BTs.22