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TSD / Cataloging and Metadata Management: Fundamentals of the NLM® Classification

General Principles

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Primary Subject(s) not in Classification Index


  • When the MeSH term is not listed in the NLM Classification index, locate the broader term under which the primary MeSH term is treed and use that class number (Cf. Module 2—Introduction to Medical Subject Headings (MeSH))
    • For example, the MeSH term Iris Neoplasms is not in the Classification index. It is treed under Uveal Neoplasms which is in the index classed at WW 240. Iris Neoplasms would also be classed at WW 240

  • Sometimes there are complex situations where a term is treed in more than one place

  • Read the MeSH scope note, annotation, and previous indexing field for the chosen term and for that of the next higher terms in the tree

  • Determine the context in which the term is used in the item being cataloged (i.e., determine the primary focus)

  • Example:
    • The MeSH term Auriculotherapy is not in the NLM Classification index
    • Although it trees under Complementary Therapies (which is classed at WB 880-962), per the scope note and previous indexing, it is closely associated with ear acupuncture (WB 369.5.E2) and should be classed there


Last Reviewed: April 16, 2021