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

Form Numbers

Page 1 of 1


Form Numbers

  • Range of numbers in an NLM classification schedule used to classify material by publication type or topical subheading
    • Usually numbers 1-49
    • Sometimes sections within a schedule (e.g. WO 201-233.1)
  • Some numbers in the range of 1 through 49 reflect format and content types, others are for material with a special topical emphasis, for example:
    • 18 is for education
    • 21 is for the profession or specialty
    • 33 is for discussion of law
  • Some main schedules are divided into sections with form numbers in each section. For example, within the QV schedule for Pharmacy and Pharmaceutics, form numbers QV 701-735 are used instead of the numbers QV 1-39 that are used for the rest of the Pharmacology schedule

Common Form Numbers (this is not a comprehensive list)

Classification NumbersPublication Type or Specific Aspects
1 Organizations, Societies
5-7 Collected Works
11 History
13 Abbreviations, Dictionary, Encyclopedia
15 Classification, Phrases, Terminology
16 Statistics, Tables, Surveys
17 Atlas, Pictorial Work
18 Education
18.2 Examination Questions, Problems and Exercises, Outline, Programmed Instruction
22-22.1 Directory
25 Laboratory Manual
32-33.1 Legislation
39/49 Handbook


Last Reviewed: January 17, 2024