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Structure of NLM Classification

Two Major Divisions of the Online NLM Classification:

• Schedule—Topical groupings of classification numbers
• Index—Single alphabetical index to the schedules which consists primarily of MeSH (Medical Subject Headings) concepts used in cataloging

Schedules—Overview

• Schedules are topical groupings of classification numbers
• The NLM Classification includes schedules permanently excluded from Library of Congress Classification (LCC): QS-QZ; W-WZ
• NLM class numbers are alphanumeric notations patterned after LCC

Schedules—Organization

   There are 36 schedules which denote broad subject categories:

• Preclinical Sciences (QS-QZ)
• General Health and Medicine (W-WB)
• Communicable Diseases; Medicine in Selected Environments (WC-WD)
• Body Systems (WE-WL)
• Specialty Areas (WM-WY)
• History (WZ; 19th Century)