National Library of Medicine Classification

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National Library of Medicine Classification

• Professor Yan Ma

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National Library of Medicine Classification
Background

• NLM classification is an example of a
  special-subject classification system that was
  expressly designed to be fully compatible with an
  extensive, existing general classification system
  (LCC).
• NLMC follows LCC in both style of classification
  and general pattern of notation.

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National Library of Medicine Classification
Background

• NLMC develops its own classification scheme for
  medicine and related subjects, fitting into LC's
  vacant class W.
• NLMC develops its own scheme for the pre-clinical
  sciences using LCC's vacant subclasses QS - QZ (Q
  is science).
• LC also agreed that W and QS-QZ would be
  permanently excluded from LCC.

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Basic Rules for NLM Classification

• 1. The class number assigned to a work is
  determined by the main focus or subject content
  of the work.
• 2. A work dealing with several subjects that fall
  into different areas of the classification is
  classed by emphasis, or if emphasis is lacking,
  by the first subject treated in the work.

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Basic Rules for NLM Classification

• 3. A work on a particular disease is classed with
  the disease which in turn is classified with the
  organ or region chiefly affected, regardless of
  special emphasis on diet, drug, or other specific
  form of therapy.

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Advantages of Using NLM Classification

• 1. Currency in arrangement of medical material
  and in terminology.
• 2. Compatibility in terminology with MeSH.
• 3. Compatibility in notation with LCC.
• 4. The presence of NLM call numbers in both the
  NLM catalog and its online database, CATLINE.
• 5. The presence of both NLM class numbers and LCC
  class numbers.

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Structure of NLM Classification

• QS-QZ (8 subclasses)
• W contains 33 major divisions
• For example, WS schedule

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Notation of NLM Classification

• 1 or 2 capital letters followed by up to 3 Arabic
  numbers.
• For example,
• W1, QS 22.1, WW 100
• NLMC allows 1-999 integers under each main class
  or subclass, in contrast to the range of 1-9999
  in LCC.

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Cutter for NLM Classification

• NLMC uses Cutter-Sanborn Three-Figure Author
  Table. Cutter by the main entry.
• Add date to the monographs.

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Table in NLM Classification

• There is only 1 table in NLMC, which is table G
  for geographic subdivisions.
• Table G is used more widely for monographic
  titles than serial titles.

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Table in NLM Classification

• In the schedule, if there is a note "(Table G)",
  you can add a geographic number to the class
  number.
• W2 is for serials. Table G is used for serials.

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Index in NLM Classification

• The index is very helpful--a very detailed one.
  Major terms are chosen to conform with those in
  MeSH.
• Major terms are in alphabetical order with
  subterms indented under them. Each major term or
  subterm is followed by a class number or a range
  of numbers, including numbers from LCC. See also
  references are also provided under the subterms.

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Bibliography Z in NLM Classification

• The call number for a bibliography in a topic
  listed in NLM schedules begins with the letter Z,
  followed by the class number for the particular
  subject of the bibliography.

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Examples of NLMC Numbers

• The practice of pediatrics in the 1990s by Edwin
  Forman, 1991.
• WS
• 21
• F724p
• 1991

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Examples of NLMC Numbers

• Children's Memorial Hospital in Chicago by Elaine
  Marieb, 1990.
• WS
• 28
• AA1
• M334c
• 1990

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Examples of NLMC Numbers

• Self image in Child Development by Deborah Chang,
  1989.
• WS
• 105.5
• .S3
• C454s
• 1989

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Examples of NLMC Numbers

• Adolescent Medicine by Patrick Murray, 1990.
• WS
• 460
• M983a
• 1990

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Comparison of DDC, LCC, and NLMC

• Class numbers
• Notations
• Cutter numbers
• Tables DDC tables can be used for all numbers.
  LCC tables are for specific schedules. NLMC only
  has one table.

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DDC Merits and Weaknesses

• Merits
• 1. It is a practical system. it has been used
  for more than 120 years and it is the most widely
  used classification system in the world.
• 2. Relative location was invented by Dewey and it
  is now taken for granted.

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DDC Merits and Weaknesses

• Merits
• 3. The relative index brings together different
  aspects of the same subject scattered in
  different disciplines.
• 4. The pure notation of Arabic numbers is
  universally recognizable. People from many
  cultures and languages can adapt to the system
  easily.

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DDC Merits and Weaknesses

• Merits
• 5. The self-evident numerical sequence
  facilitates filing and shelving.
• 6. The hierarchical nature of the notation
  expresses the relationship between and among the
  class numbers. This characteristic particularly
  facilitates online searching. The searcher can
  broaden or narrow a search by reducing or adding
  a digit to the class number.

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DDC Merits and Weaknesses

• Merits
• 7. Use of the decimal system enables infinite
  expansion and subdivision.
• 8. The mnemonic nature of the notation helps
  library users to navigate within the system.
• 9. The continuous revision and publication of the
  schedules at regular intervals ensure the
  currency of the scheme.

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DDC Merits and Weaknesses

• Weaknesses
• 1. The Anglo-American bias is obvious. (900
  geography, 800 literature, 200 religion)
• 2. Related disciplines are often separated, e.g.,
  300 (social sciences) from 900 (geography and
  history) and 400 (languages) from 800
  (literature).

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DDC Merits and Weaknesses

• Weaknesses
• 3. The proper placements of certain subjects also
  have been questioned, e.g. library science in
  general works (000s), Psychology as a subdivision
  under philosophy (100s), and sports and amusement
  in the arts (700s)

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DDC Merits and Weaknesses

• Weaknesses
• 4. In 800, literary works by the same author are
  scattered according to literary form when most
  scholars would prefer to have them grouped
  together.
• 5. The base of 10 limits the hospitality of the
  notational system by restricting the capacity for
  accommodating subjects on the same level of a
  hierarchy to 9 divisions.

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DDC Merits and Weaknesses

• Weaknesses
• 6. The different rate of growth in various
  disciplines has resulted in a uneven structure.
  Some classes, such as 300 (social sciences), 500
  (natural sciences), and 600 (technology), have
  become overcrowded.

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DDC Merits and Weaknesses

• Weaknesses
• 7. Even though an existing subject can be
  expanded indefinitely by virtue of the decimal
  system, no new numbers can be inserted between
  coordinate numbers -- e.g., between 610 and 620
  -- even required for the accommodation of new
  subjects. The present method of introducing a
  new subject is to include it as a subdivision
  under an existing subject.

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DDC Merits and Weaknesses

• Weaknesses
• 8. While capacity for expansion is infinite, it
  also results in lengthy numbers for specific and
  minute subjects. The long numbers have been
  found inconvenient, particularly when the system
  is used as a shelving device.

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DDC Merits and Weaknesses

• Weaknesses
• 9. Relocations and completely revised (i.e.,
  phoenix) schedules while necessary to keep up
  with knowledge, create practical problems in
  terms of reclassification for libraries using the
  scheme.

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LCC Merits and Weaknesses

• Merits
• 1. It is a practical system that has proved to be
  satisfactory. "It is a triumph for pragmatism."
• 2. It is based in the literary warrant of the
  materials in the LC collection, the nature and
  content of which are a reasonable parallel to
  those in academic and research libraries.

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LCC Merits and Weaknesses

• Merits
• 3. It is largely an enumerative system that
  requires minimal notational synthesis.
• 4. Each schedule was developed by subject
  specialists rather than by a "generalist" who
  cannot be an expert in every field.

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LCC Merits and Weaknesses

• Merits
• 5. Its notation is compact and hospitable.
• 6. There are frequent additions and changes,
  stemming for most part from what is needed in the
  day-to-day cataloging work at LC, and these are
  made readily available to the cataloging
  community.

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LCC Merits and Weaknesses

• Merits
• 7. The need for reclassification of large blocks
  of materials is kept to a minimum because, to
  ensure stability of class numbers, few structural
  changes have been made over the years.

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LCC Merits and Weaknesses

• Weaknesses
• 1. Its scope notes are inferior to those of DDC.
• 2. There is much national bias in emphasis and
  terminology.
• 3. Too few subjects are seen as compounds.
  Multitopical or multielement works for which
  specific provisions have not yet been made cannot
  be classified with precision.

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LCC Merits and Weaknesses

• Weaknesses
• 4. Alphabetical arrangements are often used in
  place of logical hierarchies.
• 5. There is no clear and predictable theoretical
  basis for subject analysis.
• 6. As a result of maintaining stability, parts of
  the classification are obsolete in the sense that
  structure and collocation do not reflect current
  conditions.

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LCC Merits and Weaknesses

• Weaknesses
• 7. It is expensive to keep an up-to-date working
  collection of schedules, supplements, new
  announcements of changes, and accumulations of
  additions and changes.

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Summary

• LCC can be a shelf device while DDC can serve as
  a retrieval device since OCLC has bought DDC. DDC
  is now available Web-based format via CORC.
• In DDC, you can attach a form device from a
  table, any table can be used.
• In LCC, you tend to have a screen of numbers.

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Summary

• In DDC, Geographic and Historical numbers are
  different, i.e., 910, 930, 999
• In LCC, Geographic and Historical are combined.
• LCC numbers are not expressive, but you need to
  look at the indention, finding the meaning of
  those numbers.