Fact Sheet
NLM Classification

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The NLM Classification Online

Beginning with the 2002 edition, the National Library of Medicine Classification is being published annually in electronic form. Publication of printed editions ceased with the 5^th revised edition, 1999.

The Index to the NLM Classification consists primarily of MeSH® concepts used in cataloging. It includes concepts first appearing in the latest edition of MeSH and other older concepts as warranted by literature cataloged. Schedule numbers are added or revised to reflect changes in the biomedical and related sciences.

The new online environment offers many advantages over print, including hyperlinks between terms and the MeSH Browser and class numbers; however, the biggest improvement will be in NLM's ability to keep the Classification current with changes in MeSH.

Scope and Arrangement

The National Library of Medicine Classification covers the field of medicine and related sciences. The scheme is a system of classification intended to be used for the shelf arrangement of all library materials, regardless of format. Designed as a broad classification, it is suitable for both large and small library collections and may be adapted to handle specialized collections of any size.

The NLM Classification is a system of mixed notation patterned after the Library of Congress (LC) Classification where alphabetical letters which denote broad subject categories are further subdivided by numbers. The NLM Classification utilizes schedules QS-QZ and W-WZ, permanently excluded from the LC Classification Schedules and is intended to be used with the LC schedules which supplement the NLM Classification for subjects bordering on medicine and for general reference materials. The LC schedules for Human Anatomy (QM), Microbiology (QR), and Medicine (R) are not used at all by the National Library of Medicine since they overlap the NLM Classification.

The headings for the individual schedules are given in brief form (e.g., WE - Musculoskeletal System; WG - Cardiovascular System) and together they provide an outline of the subjects that constitute the NLM Classification. These headings are interpreted broadly and include the physiological system, the specialty or specialties connected with them, the regions of the body chiefly concerned and subordinate related fields. The Classification is hierarchical, and within each schedule, division by organ usually has priority. Each main schedule, as well as some sections within a schedule, begins with a group of form numbers ranging generally from 1-49 which are used to classify materials by publication type, e.g., dictionaries, atlases, laboratory manuals, etc.

The main schedules QS-QZ, W-WY, and WZ (excluding WZ 220-270) are used to classify works published after 1913; the 19th century schedule is used for works published 1801-1913; and WZ 220-270 is used to provide century groupings for works published before 1801 and Americana. Geographic subdivision is provided for certain subjects in the NLM schedules by the application of Table G notations.

OUTLINE OF NLM CLASSIFICATION

Preclinical Sciences:

• QS Human Anatomy
• QT Physiology
• QU Biochemistry
• QV Pharmacology
• QW Microbiology and Immunology
• QX Parasitology
• QY Clinical Pathology
• QZ Pathology

Medicine and Related Subjects:

• W Health Professions
• WA Public Health
• WB Practice of Medicine
• WC Communicable Diseases
• WD Disorders of Systemic, Metabolic, or Environmental Origin, etc.
• WE Musculoskeletal System
• WF Respiratory System
• WG Cardiovascular System
• WH Hemic and Lymphatic Systems
• WI Digestive System
• WJ Urogenital System
• WK Endocrine System
• WL Nervous System
• WM Psychiatry
• WN Radiology. Diagnostic Imaging
• WO Surgery
• WP Gynecology
• WQ Obstetrics
• WR Dermatology
• WS Pediatrics
• WT Geriatrics. Chronic Disease
• WU Dentistry. Oral Surgery
• WV Otolaryngology
• WW Ophthalmology
• WX Hospitals and Other Health Facilities
• WY Nursing
• WZ History of Medicine
• 19th Century Schedule

Downloading the NLM Classification in HTML version via FTP.

For further information on the NLM Classification, write:

Cataloging Section
The National Library of Medicine
8600 Rockville Pike
Bethesda, MD 20894

Phone: 301-496-5497
Fax: 301-402-1211
Email: http://www.nlm.nih.gov/contacts/contact.html
Cataloging Section home page on the Web: http://www.nlm.nih.gov/tsd/cataloging/mainpge.html

A complete list of NLM Fact Sheets is available at:
(alphabetical list):
http://www.nlm.nih.gov/pubs/factsheets/factsheets.html
(subject list):
http://www.nlm.nih.gov/pubs/factsheets/factsubj.html

FACT SHEETS
Office of Communications and Public Liaison
National Library of Medicine
8600 Rockville Pike
Bethesda, Maryland 20894

Phone: (301) 496-6308
Fax: (301) 496-4450
email: publicinfo@nlm.nih.gov