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DB / Metadata Management Program (MMP): Fundamentals of the NLM® Classification

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Definition of classification

  • The placing of topics into categories
  • System for organizing, categorizing knowledge

Purpose of classification

  • Bring related items together in a useful sequence from the general to the specific
  • Enable customers to browse collections on a topic, either in person or online

Scope of NLM Classification

  • Covers the field of medicine and related sciences
  • Broad classification adaptable for special collections of any size or format

Historical Development

  • Print edition (1951-1999); updated infrequently
  • Online edition (2002-2016); updated annually; (2017- ) twice-yearly updates
  • PDF (2006- ); updated annually
  • Poster (2005- ); updated irregularly as needed


Last Reviewed: April 16, 2021