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NLM Classification Updated, September 23, 2019

September 23, 2019

The NLM Classification, available online at, is updated two times a year.

The 2019 winter version, published January 31, 2019, encompassed changes to the NLM Classification resulting from new and changed 2019 Medical Subject Headings (MeSH) terms as well as additional minor updates to the index and schedule.

The 2019 summer version, published September 23, 2019, encompasses the systematic review of the QW (Microbiology. Immunology) and QX (Parasitology) schedules and other miscellaneous updates.

For more information about the scope of the 2019 summer edition, see

Contact NLM for further information, questions, or comments.


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Last Reviewed: September 23, 2019