Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

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

Using the Online NLM® Classification

Page 1 of 1


Updates to NLM Classification


  • The online NLM Classification is twice a year by the NLM Classification Editorial Team

  • The Class Team’s activities include:
    • Systematic review of selected schedules
    • Additions/changes to the index based on new or replaced MeSH headings
    • Verification of selected LC class numbers used in the index
    • Resolution of classification problems raised by NLM catalogers and customers.

  • Outside subject experts/medical librarians may be consulted before major changes to the schedules are made

  • Classification problems or suggestions may be submitted to the NLM Support Center https://support.nlm.nih.gov/


Last Reviewed: April 16, 2021