1.4.3: Introduction to the Dewey Decimal Classification
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About the Introduction
1.1 This Introduction explains the basic principles and structure of the Dewey Decimal Classification (DDC) system.
1.2 The Introduction is intended to be used in conjunction with the Glossary and the Manual. The Glossary defines terms used in the Introduction and elsewhere in the Classification. The Manual offers advice on classifying in difficult areas and explains how to choose between related numbers.
Classification: What It Is and What It Does
2.1 Classification provides a system for organizing knowledge. Classification may be used to organize knowledge represented in any form, e.g., books, documents, electronic resources.
2.2 Notation is the system of symbols used to represent the classes in a classification system. In the Dewey Decimal Classification, the notation is expressed in Arabic numerals. The notation gives both the unique meaning of the class and its relation to other classes. The notation provides a universal language to identify the class and related classes, regardless of the fact that different words or languages may be used to describe the class.
History, Current Use, and Development of the Dewey Decimal Classification
3.1 The Dewey Decimal Classification—conceived by Melvil Dewey in 1873 and first published in 1876—is a general knowledge organization tool that is continuously revised to keep pace with knowledge. The system is further extended through number building, interoperable translations, association with categorized content, and mappings to other subject schemes.
3.2 The DDC is published by OCLC, Inc. The DDC is accessed through WebDewey, a frequently updated subscription service maintained by OCLC. OCLC owns all copyright rights in the Dewey Decimal Classification and licenses the system for a variety of uses.
3.3 The DDC is the most widely used classification system in the world. Libraries in more than 138 countries use the DDC to organize and provide access to their collections, and DDC numbers are featured in the national bibliographies of more than sixty countries. Libraries of every type apply Dewey numbers on a daily basis and share these numbers through a variety of means (including WorldCat). Dewey is also used in a variety of applications on the web in support of categorization, browsing, and retrieval.
3.4 The DDC has been translated into over thirty languages. Since 1988, authorized translations of the full and abridged editions of the DDC have been published or are under way in Arabic, French, German, Greek, Hebrew, Icelandic, Indonesian, Italian, Norwegian, Russian, Spanish, Swedish, Turkish, and Vietnamese. The DDC Summaries, the top three levels of the Dewey Decimal Classification system, have been translated into Afrikaans, Arabic, Chinese, Czech, French, German, Hebrew, Italian, Norwegian, Portuguese, Russian, Spanish, Swedish, and Vietnamese.
3.5 One of Dewey’s great strengths is that the system is developed and maintained in a national bibliographic agency, the Library of Congress. The Dewey editorial office is located in the Dewey Section of the Library of Congress, where classification specialists annually assign over 60,000 DDC numbers to records for works cataloged by the Library. Having the editorial office within the Dewey Section enables the editors to detect trends in the literature that must be incorporated into the Classification. The editors prepare proposed schedule revisions and expansions and forward the proposals to the Decimal Classification Editorial Policy Committee (EPC) for review and recommended action.
3.6 EPC is a ten-member international board whose main function is to advise the editors and OCLC on matters relating to changes, innovations, and the general development of the Classification. EPC represents the interests of DDC users; its members come from national, public, special, and academic libraries, and from library schools.
Overview of the Dewey Decimal Classification
CONCEPTUAL FRAMEWORK
4.1 The DDC is built on sound principles that make it ideal as a general knowledge organization tool: meaningful notation in universally recognized Arabic numerals, welldefined categories, well-developed hierarchies, and a rich network of relationships among topics. In the DDC, basic classes are organized by disciplines or fields of study. At the broadest level, the DDC is divided into ten main classes, which together cover the entire world of knowledge. Each main class is further divided into ten divisions, and each division into ten sections (not all the numbers for the divisions and sections have been used).
4.2 The main structure of the DDC is presented in the DDC Summaries. The first summary contains the ten main classes. The second summary contains the hundred divisions. The third summary contains the thousand sections. The headings associated with the numbers in the summaries have been edited for browsing purposes, and do not necessarily match the complete headings found in the schedules.
4.3 The ten main classes are:
000 Computer science, information & general works
100 Philosophy & psychology
200 Religion
300 Social sciences
400 Language
500 Science
600 Technology
700 Arts & recreation
800 Literature
900 History & geography
4.4 Class 000 is the most general class and is used for works not limited to any one specific discipline, e.g., encyclopedias, newspapers, general periodicals. This class is also used for certain specialized disciplines that deal with knowledge and information, e.g., computer science, library and information science, journalism. Each of the other main classes (100-900) comprises a major discipline or group of related disciplines.
4.5 Class 100 covers philosophy, parapsychology and occultism, and psychology.
4.6 Class 200 is devoted to religion.
4.7 Class 300 covers the social sciences. Class 300 includes sociology, anthropology, statistics, political science, economics, law, public administration, social problems and services, education, commerce, communications, transportation, and customs.
4.8 Class 400 comprises language, linguistics, and specific languages. Literature, which is arranged by language, is found in 800.
4.9 Class 500 is devoted to the natural sciences and mathematics.
4.10 Class 600 is technology.
4.11 Class 700 covers the arts: art in general, fine and decorative arts, music, and the performing arts. Recreation, including sports and games, is also classed in 700.
4.12 Class 800 covers literature, and includes rhetoric, prose, poetry, drama, etc. Folk literature is classed with customs in 300.
4.13 Class 900 is devoted primarily to history and geography. A history of a specific subject is classed with the subject.
4.14 Since the parts of the DDC are arranged by discipline, not subject, a subject may appear in more than one class. For example, “clothing” has aspects that fall under several disciplines. The psychological influence of clothing belongs in 155.95 as part of the discipline of psychology; customs associated with clothing belong in 391 as part of the discipline of customs; and clothing in the sense of fashion design belongs in 746.92 as part of the discipline of the arts.
NOTATION
4.15 Arabic numerals are used to represent each class in the DDC. The first digit in each threedigit number represents the main class. For example, 500 represents science. The second digit in each three-digit number indicates the division. For example, 500 is used for general works on the sciences, 510 for mathematics, 520 for astronomy, 530 for physics. The third digit in each three-digit number indicates the section. Thus, 530 is used for general works on physics, 531 for classical mechanics, 532 for fluid mechanics, 533 for gas mechanics. The DDC uses the convention that no number should have fewer than three digits; zeros are used to fill out numbers.
4.16 A decimal point, or dot, follows the third digit in a class number, after which division by ten continues to the specific degree of classification needed. The dot is not a decimal point in the mathematical sense, but a psychological pause to break the monotony of numerical digits and to ease the transcription and copying of the class number. A number should never end in a 0 anywhere to the right of the decimal point.
PRINCIPLE OF HIERARCHY
4.17 Hierarchy in the DDC is expressed through structure and notation.
4.18 Structural hierarchy means that all topics (aside from the ten main classes) are part of all the broader topics above them. The corollary is also true: whatever is true of the whole is true of the parts. This important concept is called hierarchical force. Certain notes regarding the nature of a class hold true for all the subordinate classes, including logically subordinate topics classed at coordinate numbers. (For a discussion of notes with hierarchical force, see paragraphs 7.10-7.17 and 7.20-7.22.)
Because of the principle of hierarchical force, hierarchical notes are usually given only once—at the highest level of application. For example, the scope note at 700 applies to 730, to 736, and to 736.4. The words “Description, critical appraisal . . .” found in the scope note at 700 also govern the critical appraisal of carving in 736 Carving and carvings, and of wood carving in 736.4 Wood. In order to understand the structural hierarchy, the classifier must investigate the schedules and tables up and down the hierarchy.
4.19 Notational hierarchy is expressed by length of notation. Numbers at any given level are usually subordinate to a class whose notation is one digit shorter; coordinate with a class whose notation has the same number of significant digits; and superordinate to a class with numbers one or more digits longer. The underlined digits in the following example demonstrate this notational hierarchy:
600 Technology (Applied sciences)
630 Agriculture and related technologies
636 Animal husbandry
636.7 Dogs
636.8 Cats
“Dogs” and “Cats” are more specific than (i.e., are subordinate to) “Animal husbandry”; they are equally specific as (i.e., are coordinate with) each other; and “Animal husbandry” is less specific than (i.e., is superordinate to) “Dogs” and “Cats.”
4.20 Sometimes, other devices must be used to express hierarchy when it is not possible or desirable to do so through the notation. A see reference leads the classifier to subdivisions of a subject located outside the notational hierarchy. A centered entry (so called because in printed editions its numbers, heading, and notes appear in the center of the page) constitutes a major departure from notational hierarchy. A centered entry is used to indicate and relate structurally a span of numbers that together form a single concept for which there is no specific hierarchical notation available. In print, centered entries are always flagged typographically by the symbol > in the number column.
Classifying with the DDC
5.1 Classifying a work with the DDC requires determining the subject, the disciplinary focus, and, if applicable, the approach or form. (For a discussion of approach or form, see paragraph 8.3.)
DETERMINING THE SUBJECT OF A WORK
5.2 Classifying a work properly depends first upon determining the subject of the work in hand. A key element in determining the subject is the author’s intent.
(A) The title is often a clue to the subject, but should never be the sole source of analysis. For example, Opera could be the title of a work on the familiar dramatic musical art form or on the web browser Opera. Likewise, a title with specific terms that are subdivisions of a field may in fact use such terms symbolically to represent the broader topic. For example, titles containing terms like chromosomes, DNA, double helix, genes, and genomes may use these terms symbolically to represent the whole subject of biochemical genetics.
(B) The table of contents may list the main topics discussed. Chapter headings may substitute for the absence of a table of contents. Chapter subheadings often prove useful.
(C) The preface or introduction usually states the author’s purpose. If a foreword is provided, it often indicates the subject of the work and suggests the place of the work in the development of thought on the subject. The book jacket or accompanying material may include a summary of the subject content.
(D) A scan of the text itself may provide further guidance or confirm preliminary subject analysis.
(E) Bibliographical references and index entries are sources of subject information.
(F) Cataloging copy from centralized cataloging services is often helpful by providing subject headings, classification numbers, and notes. Such copy appears in online services, and on the verso of the title page of many books as part of Cataloging-in-Publication (CIP) data. Data from these sources should be verified with the book in hand, since the cataloging record is based on prepublication information.
(G) Occasionally, consultation of outside sources such as reviews, reference works, and subject experts may be required to determine the subject of the work.
DETERMINING THE DISCIPLINE OF A WORK
5.3 After determining the subject, the classifier must then select the proper discipline, or field of study, of the work.
5.4 The guiding principle of the DDC is that a work is classed in the discipline for which it is intended, rather than the discipline from which the work derives. This enables works that are used together to be found together. For example, a general work by a zoologist on agricultural pest control should be classed in agriculture, not zoology, along with other works on agricultural pest control.
5.5 Once the subject has been determined, and information on the discipline has been found, the classifier will turn to the schedules. The summaries are a good means of mental navigation. The headings and notes in the schedules themselves and the Manual provide much guidance. The Relative Index may help by suggesting the disciplines in which a subject is normally treated. (For a discussion of the summaries, see paragraph 7.1; for a discussion of the Manual, see paragraphs 10.1-10.6; for a discussion of the Relative Index, see paragraphs 11.1-11.15.)
5.6 If the Relative Index is used, the classifier must still rely on the structure of the Classification and various aids throughout to arrive at the proper place to classify a work. Even the most promising Relative Index citations must be verified in the schedules; the schedules are the only place where all the information about coverage and use of the numbers may be found.
MORE THAN ONE SUBJECT IN THE SAME DISCIPLINE
5.7 A work may include multiple subjects treated separately or in relation to one another from the viewpoint of a single discipline. Use the following guidelines in determining the best placement for the work:
(A) Class a work dealing with interrelated subjects with the subject that is being acted upon. This is called the rule of application, and takes precedence over any other rule. For instance, class an analytical work dealing with Shakespeare’s influence on Keats with Keats. Similarly, class a work on the influence of the Great Depression on 20th century American art with American art.
(B) Class a work on two subjects with the subject receiving fuller treatment.
(C) If two subjects receive equal treatment, and are not used to introduce or explain one another, class the work with the subject whose number comes first in the DDC schedules. This is called the first-of-two rule. For example, a history dealing equally with the United States and Japan, in which the United States is discussed first and is given first in the title, is classed with the history of Japan because 952 Japan precedes 973 United States. Sometimes, specific instructions are given to use numbers that do not come first in the schedules. For example, at 598, the note “class comprehensive works on warm-blooded vertebrates in 599” tells the classifier to ignore the first-of-two rule and class a work on birds (598) and mammals (599) in 599, which is the comprehensive number for warm-blooded vertebrates. Also disregard the first-of-two rule when the two topics are the two major subdivisions of a subject. For example, collection systems (628.142) and distribution systems (628.144) taken together constitute 628.14 Collection and distribution systems. Works covering both of these topics are classed in 628.14 (not 628.142). Similarly, volcanoes (551.21) and earthquakes (551.22) are the two major subdivisions of 551.2 Volcanoes, earthquakes, thermal waters and gases. Works covering volcanoes and earthquakes are classed in 551.2 (not 551.21). (For a discussion of the first-of-two rule versus preference order, see paragraph 9.6; for a discussion of comprehensive numbers, see paragraphs 7.16 and 7.20-7.21.)
(D) Class a work on three or more subjects that are all subdivisions of a broader subject in the first higher number that includes them all (unless one subject is treated more fully than the others). This is called the rule of three. For example, a history of Portugal (946.9), Sweden (948.5), and Greece (949.5) is classed with the history of Europe (940).
(E) Subdivisions beginning with zero should be avoided if there is a choice between 0 and 1-9 at the same point in the hierarchy of the notation. Similarly, subdivisions beginning with 00 should be avoided when there is a choice between 00 and 0. This is called the rule of zero. For example, a biography of an American Methodist missionary in China belongs in 266 Missions. The content of the work can be expressed in three different numbers:
266.0092 biography of a missionary
266.02373051 foreign missions of the United States in China
266.76092 biography of a United Methodist Church missionary
The last number is used since it has no zero at the fourth position.
MORE THAN ONE DISCIPLINE
5.8 Treating a subject from the point of view of more than one discipline is different from treating several subjects in one discipline. Use the following guidelines in determining the best placement for the work:
(A) Use the interdisciplinary number provided in the schedules or Relative Index if one is given. An important consideration in using such an interdisciplinary number is that the work must contain significant material on the discipline in which the interdisciplinary number is found. For example, 305.231 (a sociology number) is provided for interdisciplinary works on child development. However, if a work that is interdisciplinary with respect to child development gives little emphasis to social development and a great deal of emphasis to the psychological and physical development of the child (155.4 and 612.65, respectively), class it in 155.4 (the first number in the schedules of the next two obvious choices). In short, interdisciplinary numbers are not absolute; they are to be used only when applicable. (For a discussion of interdisciplinary numbers, see paragraphs 7.16, 7.20-7.21, and 11.8-11.9.)
(B) Class works not given an interdisciplinary number in the discipline given the fullest treatment in the work. For example, a work dealing with both the scientific and the engineering principles of electrodynamics is classed in 537.6 if the engineering aspects are introduced primarily for illustrative purposes, but in 621.31 if the basic scientific theories are only preliminary to the author’s exposition of engineering principles and practices.
(C) When classifying interdisciplinary works, do not overlook the possibilities of main class 000 Computer science, information & general works, e.g., 080 for a collection of interviews of famous people from various disciplines.
Any other situation is treated in the same fashion as those found in the instructions at More Than One Subject in the Same Discipline (paragraph 5.7)
TABLE OF LAST RESORT
5.9 When several numbers have been found for the work in hand, and each seems as good as the next, the following table of last resort (in order of preference) may be used as a guideline in the absence of any other rule:
Table of last resort
(1) Kinds of things
(2) Parts of things
(3) Materials from which things, kinds, or parts are made
(4) Properties of things, kinds, parts, or materials
(5) Processes within things, kinds, parts, or materials
(6) Operations upon things, kinds, parts, or materials
(7) Instrumentalities for performing such operations
For example, surveillance by border patrols could be classed in either 363.285 Border patrols, or 363.232 Patrol and surveillance. Choose 363.285 since border patrols are a kind of police service, while patrol and surveillance are processes performed by police services.
5.10 Do not apply this table or any other guideline if it appears to disregard the author’s intention and emphasis.
How DDC 23 Is Arranged
6.1 DDC 23 is composed of the following major parts:
(A) Introduction: A description of the DDC and how to use it
(B) Glossary: Short definitions of terms used in the DDC
(C) Manual: A guide to the use of the DDC that is made up primarily of extended discussions of problem areas in the application of the DDC. Manual notes are indicated by a book icon adjacent to the schedule or table number
(D) Tables: Six numbered tables of notation that can be added to class numbers to provide greater specificity
(E) DDC Summaries: The top three levels of the DDC (F) Schedules: The organization of knowledge from 000-999
(G) Relative Index: An alphabetical list of subjects with the disciplines in which they are treated subarranged alphabetically under each entry
Key Features of the Schedules and Tables
SUMMARIES
7.1 Summaries provide an overview of the structure of classes. Three types of summaries appear in the DDC:
(A) DDC Summaries, the summaries of the top three levels of the DDC. (For a discussion of DDC Summaries, see paragraphs 4.2-4.13.)
(B) In print, two-level summaries are provided for each main class and division of the schedules and main numbers of Table 2 with subdivisions that extend beyond forty pages. See the summaries at the beginning of T2—4 Europe and 370 Education for examples of two-level summaries.
(C) Single-level summaries in the print schedules and tables provide an overview of classes whose subdivisions cover between four and forty pages. For example, 382 International commerce (Foreign trade) has the following summary
382.01-.09 Standard subdivisions
.1 General topics of international commerce
.3 Commercial policy
.4 Specific products and services
.5 Import trade
.6 Export trade
.7 Tariff policy
.9 Trade agreements
ENTRIES
7.2 Entries in the schedules and tables are composed of a DDC number in the number column, a heading describing the class that the number represents, and often one or more notes. In print, DDC numbers are listed in groups of three digits for ease of reading and copying. All entries (numbers, headings, and notes) should be read in the context of the hierarchy. (For a discussion of the principle of hierarchy, see paragraphs 4.17-4.20.)
7.3 In print, the first three digits of schedule numbers (main classes, divisions, sections) appear only once in the number column, when first used. They are repeated at the top of each page where their subdivisions continue. Subordinate numbers appear in the number column, beginning with a decimal point, with the initial three digits understood.
7.4 Table numbers are never used alone. There are six numbered tables in DDC 23:
T1 Standard Subdivisions
T2 Geographic Areas, Historical Periods, Biography
T3 Subdivisions for the Arts, for Individual Literatures, for Specific Literary Forms
T3A Subdivisions for Works by or about Individual Authors
T3B Subdivisions for Works by or about More than One Author
T3C Additional Notation for Arts and Literature
T4 Subdivisions of Individual Languages and Language Families
T5 Ethnic and National Groups
T6 Languages
Except for notation from Table 1 (which may be added to any number unless there is an instruction in the schedules or tables to the contrary), table notation may be added only as instructed in the schedules and tables. (For a detailed discussion of the use of the six tables, see paragraphs 8.3-8.20.)
7.5 Some numbers in the schedules and tables are enclosed in parentheses or square brackets. Numbers and notes in parentheses provide options to standard practice. Numbers in square brackets represent topics that have been relocated or discontinued, or are unassigned. Square brackets are also used for standard subdivision concepts that are represented in another location. Bracketed numbers should never be used. (For a discussion of options, see paragraphs 12.1-12.8; for a discussion of relocations and discontinuations, see paragraphs 7.24-7.25; for a discussion of bracketed standard subdivisions, see paragraph 7.28.)
7.6 Standard subdivisions are also bracketed under a hook number, that is, a number that has no meaning in itself, but is used to introduce specific examples of a topic. Hook numbers have headings that begin with “Miscellaneous,” “Other,” or “Specific”; and do not contain add notes, including notes, or class-here notes. For example:
652.302 Specific levels of skill
652[.30201-652.30209] Standard subdivisions
Do not use; class in 652.3001-652.3009
NOTES
7.7 Notes are important because they supply information that is not obvious in the notational hierarchy or in the heading with regard to order, structure, subordination, and other matters. Notes may appear in the record for a number or a span of numbers. Notes may also appear at the beginning of a table. Individual entries in the Manual are also considered notes.
7.8 Notes in the schedules and tables generally appear in the following order in print: definition, number-built, standard-subdivisions-are added, variant-name, scope, including, class-here, arrange, add (including subdivisions-are-added), preference, classelsewhere, see-reference, see-also reference, see-Manual and option notes. In WebDewey, the following notes are listed in the history box in reverse chronological order: revision, former-heading, relocation, discontinuation, continuation, authorization, and deprecation notes.
7.9 The notes below do the following: (A) describe what is found in the class and its subdivisions; (B) identify topics in standing room, i.e., topics with insufficient literature to have their own number; (C) describe what is found in other classes; and (D) explain changes in the schedules and tables. Other notes are described in the sections on number building (paragraphs 8.1-8.24), citation and preference order (paragraphs 9.1-9.6), the Manual (paragraphs 10.1-10.6), and options (paragraphs 12.1-12.8).
Notes in categories (A) and (C) have hierarchical force (i.e., are applicable to all the subdivisions of a particular number). Those in category (B) do not have hierarchical force.
(A) Notes That Describe What Is Found in a Class
7.10 Definition notes indicate the meaning of a term in the heading. For example:
364 Criminology
Crime and its alleviation
7.11 Scope notes indicate whether the meaning of the number is narrower or broader than is apparent from the heading. For example:
700 The arts
Description, critical appraisal, techniques, procedures, apparatus, equipment, materials of the fine, decorative, literary, performing, recreational arts
7.12 Number-built notes identify and explain the source of built numbers included in the schedules and tables. Built numbers are occasionally included in the print schedules or tables to provide additional information or to indicate exceptions to regular add instructions. For example:
353.13263 Foreign service
Number built according to instructions under 352-354
Class here consular and diplomatic services
7.13 Former-heading notes are given only when the heading associated with a class number used in previous versions of the DDC has been altered to such a degree that the new heading bears little or no resemblance to the previous heading, even though the meaning of the number has remained substantially the same. For example:
523.48 *Neptune
Former heading: Trans-Neptunian planets
7.14 Variant-name notes are used for synonyms or near synonyms. For example:
332.32 Savings and loan associations
Variant names: building and loan associations, building societies, home loan associations, mortgage institutions
7.15 Class-here notes list major topics in a class. These topics may be broader or narrower than the heading, overlap it, or define another way of looking at essentially the same material. Topics in class-here notes are considered to approximate the whole of the class. For example:
371.192 Parent-school relations
Class here parent participation in schools; comprehensive works on teacher-parent relations
Standard subdivisions may be added for any topic in a class-here note. (For a detailed discussion of the use of standard subdivisions for concepts that approximate the whole of a class, see paragraphs 8.3-8.12 and the beginning of Table 1.)
7.16 Class-here notes are also used to indicate where interdisciplinary and comprehensive works are classed. Interdisciplinary works treat a subject from the perspective of more than one discipline. For example:
391 Costume and personal appearance
Class here interdisciplinary works on costume, clothing (apparel, garments), fashion; casual wear (sportswear)
641.815 Breads and bread-like foods
Class here yeast breads, comprehensive works on baked goods (stated)
T2—4115 Highland
Class here *Scottish Highlands (implied)
7.17 Entries in the taxonomic schedules in 579-590 may have two class-here notes. The first class-here note contains scientific taxonomic names. The second one contains common names. For example:
588.2 Bryopsida
Class here Bryales
Class here true mosses, comprehensive works on mosses
(B) Including Notes (Notes That Identify Topics in Standing Room)
7.18 Including notes identify topics that have “standing room” in the number where the note is found. Standing room numbers provide a location for topics with relatively few works written about them, but whose literature may grow in the future, at which time they may be assigned their own number. For example:
362.16 Extended care medical facilities
Including convalescent homes, sanatoriums for persons suffering from chronic diseases
Standard subdivisions cannot be added for topics in standing room, nor are other number-building techniques allowed.
7.19 Entries in the taxonomic schedules in 579-590 may have two including notes. The first including note contains the scientific taxonomic names. The second one contains common names. For example:
593.55 Hydrozoa
Including Chondrophora, Hydroida, Milleporina, Pteromedusae, Siphonophora, Stylasterina, Trachylina
Including hydras, Portuguese man-of-war
(C) Notes That Describe What Is Found in Other Classes
7.20 Class-elsewhere notes lead the classifier to interrelated topics, or distinguish among numbers in the same notational hierarchy. They are used to show preference order, to lead to the comprehensive or interdisciplinary number, to override the first-of-two rule, or to lead to broader or narrower topics in the same hierarchical array that might otherwise be overlooked. They may point to a specific number, or to a concept scattered throughout the schedules. All notes that begin with the word “class” are class-elsewhere notes, except when they begin with “class here.” For example:
641.7 Specific cooking processes and techniques
Class specific processes applied to specific materials in 641.6; class specific processes applied to specific kinds of dishes, preparing beverages in 641.8
370.15 Educational psychology
Class interdisciplinary works on psychology in 150. Class psychology of a specific topic in education with the topic, plus notation 019 from Table 1, e.g., psychology of special education 371.9019
155.4 Child psychology
Class interdisciplinary works on child development in 305.231
7.21 See references lead from a stated or implied comprehensive number for a concept to the component (subordinate) parts of that concept in a different notational hierarchy. See references also lead from the interdisciplinary number for a concept to treatment of the concept in other disciplines. A see reference may point to a specific number, or to a concept scattered throughout the schedules. Each see reference begins with the word “For.” For example:
577.7 Marine ecology
Class here saltwater ecology
For salt lake ecology, see 577.639
For saltwater wetland and seashore ecology, see 577.69
305.4 Women
Class here interdisciplinary works on women, on females
For a specific aspect of women not provided for here, see the aspect, e.g., women’s suffrage 324.623
Throughout Table 2, see references lead from the implied comprehensive number for a jurisdiction, region, or feature to its subordinate parts in other classes. For example:
T2—4115 Highland
Class here *Scottish Highlands
*For a specific part of this jurisdiction, region, or feature, see the part and follow instructions under T2—4-T2—9
7.22 See-also references lead the classifier to related topics. They are reminders that minor differences in wording and context can imply differences in classification. For example:
597.56 *Salmon
See also 597.7 for Australian salmon
(D) Notes That Explain Changes or Irregularities in the Schedules and Tables
7.23 In WebDewey, revision notes warn users that there have been changes in the subdivisions of a class since the previous edition and indicate the degree of revision: new schedule, complete revision, or extensive revision. These notes appear in the history box; notes for changes before 2017 may vary in wording and format, or be missing entirely. (For an example of a new schedule note, see 777 Cinematography and videography. For an example of an extensive revision note, see 583-584 Angiosperms.)
7.24 In WebDewey, the shifting of a topic from one number to another number in the same hierarchy is indicated in discontinuation notes and continuation notes. These notes appear in the history box; notes for changes before 2017 may vary in wording and format, or be missing entirely.
Discontinuation notes indicate that one or more topics have been moved to a superordinate number (a more general number) or have been dropped entirely. Notes at both ends of the discontinuation identify the old and new locations for those topics moved to the superordinate number. The discontinued topics need not be mentioned in the heading, including note, or class-here note at the new location. For example:
344.054 Matters concerning public morals and customs
Law of premarital and extramarital relations as social problem discontinued from 344.0548 2017-08-02, Edition 23
372[.455] [Unassigned]
Speed reading discontinued because without meaning in context 2011-04, Edition 23
623.746 Heavier-than-air aircraft
Rocket planes discontinued from 623.746045 2016-06, Edition 23
Continuation notes indicate that one or more topics have shifted to a subordinate number (a more specific number). Notes at both ends of the continuation identify the old and new locations. The continued topics need not be mentioned in the heading, including note, or class-here note at the new location. For example:
005.8 *Computer security
Digital rights management, electronic signatures continued to 005.82 2016-11-16, Edition 23
005.82 *Countermeasures to threats
Including digital rights management, electronic signatures
Digital rights management, electronic signatures continued from 005.8 2016-11-16, Edition 23
7.25 In WebDewey, the shifting of a topic from one number (the old location) to another number (the new location), where the new number is in neither the upward nor the downward notational hierarchy of the old number (that is, the new number is neither a superordinate nor a subordinate number of the old number) is indicated in relocation notes. These notes appear in the history box; notes for changes before 2017 may vary in wording and format, or be missing entirely
Notes at both ends of the relocation identify the old and new locations. The relocated topics need not be mentioned in the heading, including note, or class-here note at the new location. For example:
T2—[755811] [Unassigned]
Clifton Forge relocated to T2—755816 2008, Edition 22
T2—755816 Alleghany County
Clifton Forge formerly located in T2—755811 2008, Edition 22
302.231 Digital media
Electronic publications relocated to 302.232 2014-01-07, Edition 23
302.232 Print media
Electronic publications formerly located in 302.231 2014-01-07, Edition 23
7.26 In WebDewey, the approval of a number (possibly reused) in the schedules or tables to provide further subdivisions of an existing number is indicated in authorization notes. These notes appear in the history box and only exist from 2017 onward.
A newly authorized number typically results when one or more topics are continued from a superordinate number, but may also involve the relocation of one or more topics. A note at the authorized number indicates when the authorization occurred; the date can be used to identify notes for topics that were continued or relocated into the number.
796.817 Kickboxing
Kickboxing continued from 796.81
2017-07-07, Edition 23
796.817 authorized
2017-07-07, Edition 23
7.27 In WebDewey, the invalidation of a number previously authorized for use is indicated in deprecation notes. These notes appear in the history box and only exist from 2017 onward.
Numbers that have been deprecated appear in square brackets with the caption “Unassigned.” A note at the deprecated number indicates when the deprecation occurred; the date can be used to identify notes for topics that were discontinued or relocated out of the number.
363[.42] [Unassigned]
Gambling as a social problem relocated to 362.27
2017-08-02, Edition 23
363.42 deprecated
2017-08-02, Edition 23
7.28 Do-not-use notes instruct the classifier not to use all or part of the regular standard subdivision notation, but instead to use a special provision or standard subdivision notation at a broader number. When the whole standard subdivision is removed from use, the note appears under a bracketed standard subdivision; when only part of the standard subdivision is displaced, the part displaced is specified. For example:
374[.809] History, geographic treatment, biography
Do not use; class in 374.9
320.409 History and biography
Do not use for geographic treatment; class in 320.41-320.49
Do-not-use notes are also used to instruct the classifier not to use all or part of an add table provision, but instead to use a special provision.
343.014 *Discipline and conduct
Including desertion
Subdivisions are added for either or both topics in heading
For discipline and conduct of a specific service other than the army in general, see the service in 343.015-343.019, e.g., discipline and conduct of mercenary troops 343.015354, naval discipline and conduct 343.01913
*Add as instructed under 342-347
343[.0140269] Courts and procedure
Do not use; class in 343.0143
Do-not-use notes involve (1) a base number and (2) notation that could be added to the base number if the do-not-use note were not present (hereafter “bracketed added notation”). As shown above, the bracketed added notation can be either a standard subdivision or notation from an add table.
A do-not-use note does not have hierarchical force for numbers in the downward hierarchy of the base number. Unless it has its own do-not-use note, notation that cannot be added to one base number can be added to base numbers in its downward hierarchy. Consider, for example:
069[.50288] Maintenance and repair
Do not use; class in 069.53
The displacement of maintenance and repair from 069.50288 to 069.53 Maintenance, conservation, preservation, restoration, display, arrangement, storage, transportation does not mean that maintenance and repair is displaced for all numbers subordinate to 069.5. Numbers for maintenance and repair of 069.55 Study collections, 069.56 Lending and rental collections, and 069.57 Collections of secondary materials would be built following standard practice by adding T1—0288 to these respective base numbers.
For a standard subdivision to be displaced throughout a hierarchy, either the do-not-use note must be repeated or other instructions must be given to effect the displacement. For example:
220[.03] Dictionaries, encyclopedias, concordances
Do not use for dictionaries and encyclopedias; class in 220.3 Do not use for concordances; class in 220.4-220.5
The do-not-use note at 220.03 does not have hierarchical force throughout the 220s. However, standard subdivision T1—03 Dictionaries, encyclopedias, concordances is displaced throughout almost all of the 220s because of similar entries at 221.03 and 225.03 and because nearly all entries under 222-224 and 226-229 add as instructed under 221-229, where notation is added following the patterns under 220.
A do-not-use note does have hierarchical force, however, with respect to numbers in the downward hierarchy of the bracketed added notation. When a do-not-use note indicates that a specific standard subdivision or add table notation cannot be added to a base number, standard subdivisions or add table notation in the downward hierarchy of the bracketed added notation are also blocked from being added to that base number. For example:
155[.40862] People by social and economic levels
Do not use; class in 155.456
Do-not-notes are not needed at 155.408621, 155.408622, and 155.4086222, etc., to displace these standard subdivisions to 155.456. That displacement is governed by the application of hierarchical force of the do-not-use note at 155.40862 to all standard subdivisions subordinate to T1—0862.
Number Building
8.1 The classifier will often find that to arrive at a precise number for a work it is necessary to build or synthesize a number that is not specifically listed in the schedules. Such built numbers allow for greater depth of content analysis. They are used only when instructions in the schedules make them possible (except for standard subdivisions, which are discussed in paragraphs 8.3-8.12). Number building begins with a base number (always stated in the instruction note) to which another number is added.
8.2 There are four sources of notation for building numbers: (A) Table 1 Standard Subdivisions; (B) Tables 2-6; (C) other parts of the schedules; and (D) add tables in the schedules.
(A) Adding Standard Subdivisions from Table 1
8.3 A standard subdivision represents a recurring physical form (such as a dictionary, periodical, or index) or approach (such as history or research) and thus is applicable to any subject or discipline that covers or approximates the whole of the meaning of the number. Here are a few examples with the standard subdivision concept underlined (in some cases an extra 0 precedes the standard subdivision according to instructions found in the schedules):
150.1 Philosophy and theory of psychology
230.003 Dictionary of Christianity
340.02573 Directory of lawyers in the U.S.
405 Periodical on language
507.8 Use of apparatus and equipment in the study and teaching of science, e.g., science fair projects
624.0285 Computer applications in civil engineering
796.912092 Biography of a figure skater
808.0071 Teaching of rhetoric
Further instructions on using Table 1 are found at the beginning of Table 1. See also Manual notes on selected standard subdivisions.
8.4 Standard subdivisions are not usually listed in the schedules except where needed to fill out three-digit numbers, e.g., 605 Serial publications, and in a few other instances. Standard subdivisions may be listed in the schedules when the subdivisions have extended or narrowed meanings. For example:
535.220287 Testing and measurement (extended meaning)
Class here photometry
390.088 [Customs of] Religious groups (narrowed meaning)
Do not use for occupational groups; class in 390.4
Standard subdivisions may also be listed to introduce an expansion featuring special notation (the subdivisions in the expansion are not standard subdivisions). Such standard subdivisions are accompanied by a special note. For example:
370.1 Philosophy and theory, education for specific objectives, educational psychology
Notation 01 from Table 1 as modified below
Sometimes, standard subdivisions are listed because references to other classes or the Manual are required. For example:
507.2 Research
Class research covering science in general in 001.4
See Manual at 500 vs. 001
507.21 Research methods
Class scientific method as a general research technique in 001.42
8.5 When standard subdivision notation from Table 1 is listed in Tables 2-6 and in the schedules, all of the notation’s notes and subdivisions as given in Table 1 are applicable unless other instructions are given. Other Table 1 notation that is not listed in the schedules may also be used. For example, the fact that 610.7 is listed, but not 610.8 or the subdivisions of 610.7, does not exclude the use of 610.8 or 610.71.
8.6 Notation from Table 1 Standard Subdivisions may be added to any number in the schedules unless there is a specific instruction to the contrary. The classifier should never use more than one zero in applying a standard subdivision unless instructed to do so. If more than one zero is needed, the number of zeros is always indicated in the schedules. When using standard subdivisions with numbers built by adding from Tables 2-6 or other parts of the schedules, be sure to check the table or schedule used for the segment preceding the standard subdivision for special instructions on the number of zeros.
8.7 The most important caveat with respect to standard subdivisions is that they are added only for works that cover or approximate the whole of the subject of the number. For example, a work on mockingbirds of California should be classed in 598.844, the number for birds of the Mimidae family (not 598.84409794, the number for birds of the Mimidae family in California). The classifier should not attempt to specify California because mockingbirds are in the including note under 598.844 and therefore do not approximate the whole of 598.844 Mimidae. Likewise, class a work on the De Havilland 98 Mosquito (a specific British World War II fighter-bomber) in the number for fighter-bombers 623.7463 (not 623.7463094109044, the number for British fighter-bombers in World War II).
8.8 Standard-subdivisions-are-added notes indicate which topics in a multiterm heading may have standard subdivisions added for them because the designated topics are considered to approximate the whole of the subject. For example:
639.2 Commercial fishing, whaling, sealing
Standard subdivisions are added for commercial fishing, whaling, sealing together; for commercial fishing alone
Standard-subdivisions-are-added notes do not have hierarchical force beyond the standard subdivisions associated with the number itself. For example, the note under 639.2 governs the application of standard subdivisions to 639.2 itself, but not to 639.21- 639.29.
8.9 Do not add multiple standard subdivisions to the same number except when specifically instructed to do so, and in the following instances. Standard subdivisions may be added to subdivisions of T1—04 Special topics that are specifically listed in the schedules. For example, standard subdivisions may be added to 155.9042 Stress, a subdivision of 155.904 Special topics in environmental psychology.
Standard subdivisions may also be added to special notation in the regular standard subdivision sequence. For example, under 370.1, there is an expansion for educational objectives at 370.11 Education for specific objectives. Standard subdivisions may be added to 370.11 and its subdivisions, since 370.11 and its subdivisions are special notation.
Standard subdivision concepts may be displaced to a special provision in the regular sequence of standard subdivisions or elsewhere; in either case, standard subdivisions may be added to the special provision. For example, 370.19 Psychological principles has been completely displaced to 370.15 Educational psychology, where the regular meaning of 370.15 (scientific principles) has been discontinued to 370.1. Notation 03 from Table 1, the standard subdivision for encyclopedias, may be added to 370.15 Educational psychology to represent an encyclopedia of educational psychology 370.1503.
The full range of standard subdivisions may also be added to standard subdivision concepts displaced to notation outside the regular sequence of standard subdivisions, e.g., the management of penal institutions in Great Britain 365.941068 (geographic treatment of penal institutions has been displaced from 365.09 to 365.9).
8.10 In many places in the schedules, there are numbers outside the regular sequence of standard subdivisions that look like standard subdivisions but are not standard subdivisions. If additional subdivisions are intended to be used at the special provision, an add note is provided. For example, at 027.009, a regular standard subdivision, geographic treatment is displaced to 027.01-027.09:
027.009 History and biography
Do not use for geographic treatment; class in 027.01-027.09
027.01-027.09 *Geographic treatment
Add to base number 027.0 notation 1-9 from Table 2, e.g., libraries in France 027.044
The special provision for geographic treatment at 027.01-027.09 is not a standard subdivision. If appropriate, standard subdivisions may be added to the resulting notation, e.g., libraries in France in the late 20th century 027.04409045.
8.11 Standard subdivisions should not be used where redundant, i.e., where the subdivision means the same as the base number, or where application of the standard subdivision would needlessly segregate material by aspects not emphasized by the author. For example, do not add notation 024694, which represents the subject for carpenters, to topics in 694, the number for carpentry, since works on a subject are written primarily for its practitioners. Likewise, do not add the subdivision of notation 0905 for the latest historical period to general works on a subject to represent the state-of-the-art because most users will expect to find such works in the main number. Special care should be taken in adding standard subdivisions to built numbers, since the standard subdivision applies to the whole number and not just to part of the number.
8.12 The table of preference at the beginning of Table 1 yields to two other rules, the rule of application and the rule of zero. By the rule of application, teaching financial management in hospital administration is classed in 362.110681, not 362.11071, even though notation 07 is above notation 068 in the table of preference. The rule of zero overrides the table of preference when standard subdivisions are displaced to notation outside the regular sequence of standard subdivisions (notation at nonzero positions or notation with fewer zeros), e.g., management of prisons in Great Britain 365.941068, not 365.068 as would be the case if prisons in Great Britain were classed in 365.0941. (For a discussion of the rule of application and rule of zero, see paragraph 5.7; for a discussion of displaced standard subdivisions, see paragraphs 7.28 and 8.9.)
(B) Adding from Tables 2-6
8.13 The classifier may be instructed to add notation from Tables 2-6 to a base number from the schedules or to a number from a table. A summary of the use of each table follows. Further instructions on using Tables 2-6 are found at the beginning of each table (for example, T2—0). See also the Manual notes for Tables 2-6.
8.14 Table 2 Geographic Areas, Historical Periods, Biography. The major use of Table 2 is with notation 09 from Table 1, where it can be added to every number in the schedule unless there are specific instructions to the contrary. For example, reading instruction in the primary schools of Australia is 372.40994 (372.4 reading instruction in primary schools + 09 History, geographic treatment, biography from Table 1 + 94 Australia from Table 2). Notation from Table 2 is also added through the use of other standard subdivisions from Table 1 (e.g., standard subdivisions 025, 074).
8.15 Area notation is sometimes added directly to schedule numbers, but only when specified in a note. For example:
373.3-373.9 Secondary education in specific continents, countries, localities
Add to base number 373 notation 3-9 from Table 2, e.g., secondary schools of Australia 373.94
8.16 Table 3 Subdivisions for the Arts, for Individual Literatures, for Specific Literary Forms. These subdivisions are used in class 800 as instructed, usually following numbers for specific languages in 810-890. Table 3C subdivisions are also added as instructed to numbers in Table 3B, 398.2-398.3, 659.1, 700.4, 741.5, 791.4, 794.8, and 808-809.
8.17 Table 4 Subdivisions of Individual Languages and Language Families. These subdivisions are used as instructed in class 400, following numbers for designated specific languages or language families in 420-490.
8.18 Table 5 Ethnic and National Groups. Notation from Table 5 is added through the use of standard subdivision 089 from Table 1, e.g., Ceramic arts of Chinese artists throughout the world is 738.089951 (738 Ceramic arts + 089 Ethnic and national groups from Table 1 + 951 Chinese from Table 5).
8.19 Table 5 notation may also be added directly to schedule numbers, but only when specified in a note. For example: 781.621-781.629 Folk music of specific ethnic and national groups Add to base number 781.62 notation 1-9 from Table 5, e.g., Spanish folk music 781.6261; then add further . . . 8.20 Table 6 Languages. The major uses of Table 6 notation are to provide the basis for building a specific language number in 490 (to which notation from Table 4 is sometimes added) and to provide the basis for building a specific literature number in 890 (to which notation from Table 3 is sometimes added). Table 6 notation is also used in Table 2 under —175 Regions where specific languages predominate, and at various points in the schedules.
(C) Adding from Other Parts of the Schedules
8.21 There are many instructions to make a direct addition to a number from another part of the schedules. For example:
809.935 Literature emphasizing subjects
Add to base number 809.935 notation 001-999, e.g., religious works as literature 809.9352, biography and autobiography as literature 809.93592
In this example, the 2 in 809.9352 comes from 200 Religion, the 92 in 809.93592 from 920 Biography, genealogy, insignia.
8.22 In many cases, part of a number may be added to another number upon instruction. For example:
372.011 Primary education for specific objectives
Add to base number 372.011 the numbers following 370.11 in 370.111-370.119, e.g., character education 372.0114
In this example, 4 comes from 370.114 Moral, ethical, character education. Sometimes numbers are taken from more than one place in the schedules; in such cases the procedure for the second addition is the same as for the first.
(D) Adding from Tables Found in the Schedules
8.23 Add tables in the schedules provide numbers to be added to designated schedule numbers (identified by a symbol [*or † or ‡] and accompanying instruction); these tables must be used only as instructed. For example:
616.973 *Contact allergies
Class here allergic contact dermatitis, allergies of skin
The asterisk in the entry above leads to the following instruction: “*Add as instructed under 616.1-616.9.” The add table at 616.1-616.9 is used only for diseases tagged with an asterisk or for diseases in class-here notes under headings tagged with an asterisk. Notation from the add table, such as 061 Drug therapy, may be used for 616.973 Contact allergies (tagged with an asterisk) and for allergic contact dermatitis and allergies of skin (in the class-here note).
8.24 Subdivisions-are-added notes indicate which terms in a multiterm heading may have subdivisions applied to them. For example:
616.51 *Dermatitis, photosensitivity disorders, urticaria
Subdivisions are added for dermatitis, photosensitivity disorders, urticaria together; for dermatitis alone
Citation and Preference Order
9.1 Citation and preference order must be considered when multiple aspects or characteristics of a subject (such as age, area, gender, historical periods, national origin) are provided for in the Classification, and a single work treats more than one of them.
CITATION ORDER
9.2 Citation order allows the classifier to build or synthesize a number using two or more characteristics (facets) as specified in instruction notes. Success in building a DDC number requires determining which characteristics apply to a specific work, and then determining from the instructions in the schedule the sequence in which the facets will be ordered. 9.3 Citation order is always carefully detailed in number-building instructions. For example:
909.041-.049 [History with respect to] Specific ethnic and national groups
Add to base number 909.04 notation 1-9 from Table 5 for the group only, e.g., world history of Jews 909.04924; then add 0* and to the result add the numbers following 909 in 909.1-909.8, e.g., world history of Jews in 18th century 909.0492407
For a work on the world history of the Jews in the 18th century, this note stipulates the following citation order for the individual facets of the full subject: world history + specific ethnic or national group + historical period. The historical period is introduced by the facet indicator 0.
PREFERENCE ORDER
9.4 If there is no provision to show more than one of the aspects or characteristics, it is a matter of preference (because a choice must be made among several characteristics)
Preference notes supply either an instruction or table establishing the order in which to make the choice. An example of a preference instruction is found at 305.9:
305.9 People by occupation and miscellaneous social statuses; people with disabilities and illnesses, gifted people
Unless other instructions are given, class a subject with aspects in two or more subdivisions of 305.9 in the number coming last, e.g., unemployed librarians 305.9092 (not 305.90694)
In this case, the base subject is a group of persons; the two characteristics are employment status and occupational status. The occupation of librarian (305.9092) falls after unemployed status (305.90694) in the DDC hierarchy; following the instructions in the preference note, the characteristic that must be chosen is librarian (305.9092). (For an example of a preference instruction using a class-elsewhere note, see paragraph 7.20.)
9.5 An example of a table indicating preference order is found at 305:
305 Groups of people
Unless other instructions are given, observe the following table of preference, e.g., African American male youths 305.235108996073 (not 305.3889607300835 or 305.896073008351):
People with disabilities and illnesses, gifted people 305.908
Age groups 305.2
People by gender or sex 305.3-305.4
People by social and economic levels 305.5
Religious groups 305.6
Ethnic and national groups 305.8
Language groups 305.7
People by occupation and miscellaneous social statuses (except 305.908) 305.9
9.6 Classifiers often must distinguish between preference order instructions and the first-oftwo rule in the same schedule. If the work treats two subjects, apply the first-of-two rule. If the work treats two aspects of the same subject, apply the preference order instructions. When the preference order instruction is to class with the last, the first-of-two rule and the preference order instructions may lead the classifier in opposite directions. For example, a bibliography of newspapers and pamphlets giving equal treatment to each would be classed according to the first-of-two rule in 011.33 (bibliography of pamphlets) rather than 011.35 (bibliographies of newspapers). A bibliography of microform newspapers (i.e., newspapers in microform form) would be classed according to the preference note at 011.1-011.8: “Unless other instructions are given, class a subject with aspects in two or more subdivisions of 011.1-011.8 in the number coming last . . .”; thus, the bibliography of microform newspapers would be classed in 011.36 (bibliographies of microforms) rather than 011.35 (bibliographies of newspapers). (For a discussion of the first-of-two rule, see paragraph 5.7.)
The Manual
10.1 The Manual gives advice on classifying in difficult areas and provides guidance on choosing between related numbers.
10.2 See-Manual references in the schedules and tables refer the classifier to the Manual for additional information about a certain number, range of numbers, or choice among numbers. In some cases, the see-Manual reference refers only to a portion of a longer Manual note, or topic narrower than the numbers in the heading, e.g., “See Manual at 930-990: Historic preservation.” The see-Manual reference is repeated in the entries for each of the numbers or number spans covered in the Manual note. For example, “See Manual at 004.21 vs. 004.22, 621.392” is listed in the entries for 004.21, 004.22, and 621.392.
10.3 Brief Manual-like notes are sometimes given directly in the schedule or table entry. For example:
631.583 Controlled-environment agriculture
Most works on use of artificial light in agriculture will be classed in 635.0483 and 635.9826
ARRANGEMENT AND FORMAT OF THE MANUAL
10.4 The Manual is arranged by table and schedule numbers, with the broadest span coming before entries for narrower spans or individual numbers. Manual notes are entered under the preferred or “if-in-doubt” number. If there is no if-in-doubt number, prefer the interdisciplinary number.
10.5 The Manual note heading summarizes the contents of the note. The terms in the Manual note headings need not match the terms associated with the same number(s) in the tables and schedules if the note is narrower than the number, or the note refers to more than one number. For example:
510 Mathematics
510, T1—0151 vs. 003, T1—011 Systems
10.6 If the Manual note is very long, or part of the note focuses on a topic narrower than the heading, subheadings may be provided. For example:
T1—068 vs. 353-354 Public administration and management in specific fields
Exceptions (subheading)
The Relative Index
11.1 The Relative Index is so named because it relates subjects to disciplines. In the schedules, subjects are distributed among disciplines; in the Relative Index, subjects are arranged alphabetically, with terms identifying the disciplines in which they are treated subarranged alphabetically under them. For example:
Hospitals 362.11
Hospitals—accounting 657.8322
Hospitals—American Revolution 973.376
Hospitals—animal husbandry 636.08321
Hospitals—architecture 725.51
Hospitals—armed forces 355.72
Hospitals—Civil War (United States) 973.776
Hospitals—construction 690.551
Hospitals—energy economics 333.7964
Hospitals—institutional housekeeping 647.9651
Hospitals—landscape architecture 712.7
Hospitals—law 344.03211
Hospitals—liability law 346.031
Hospitals—management 362.11068
Hospitals—management—law 344.03211068
Hospitals—meal service 642.56
Hospitals—pastoral theology 206.1
Hospitals—pastoral theology—Christianity 259.411
Hospitals—social theology 201.76211
Hospitals—social theology—Christianity 261.83211
Hospitals—social welfare 362.11
Hospitals—World War I 940.476
Hospitals—World War II 940.5476
In some cases the term implies rather than states the discipline. In the example above, the discipline of architecture is listed, but the discipline of military science is implied by “armed forces.”
11.2 The Relative Index is primarily an index to the DDC as a system. It includes most terms found in the schedules and tables, and terms with literary warrant for concepts represented by the schedules and tables. The Relative Index is not exhaustive. If the term sought is not found, the classifier should try a broader term, or consult the schedules and tables directly. The schedules and tables should always be consulted before a number found in the Relative Index is applied.
ARRANGEMENT AND FORMAT OF THE RELATIVE INDEX
11.3 Index entries are arranged alphabetically word by word, e.g., Birth order precedes Birthday. Entries with the same word or phrase but with different marks of punctuation are arranged in the following order:
Term
Term. Subheading
Term (Parenthetical qualifier)
Term, inverted term qualifier
Term as part of phrase
Initialisms and acronyms are entered without punctuation and are filed as if spelled as one word. Hyphens are ignored and treated as a space. Terms listed below the main headings are alphabetized even though they may be a mixture of disciplines, topical subheadings, and, to a limited extent, words that form phrases or inverted phrases when combined with the main heading.
11.4 In print, class numbers are listed in groups of three digits for ease of reading and copying. The spaces are not part of the numbers and do not represent convenient places to abridge the number.
11.5 See-also references are used for synonyms and for references to broader terms (but only when three or more new numbers will be found at the synonym or broader term), and for references to related terms (which may provide only one or two new numbers).
11.6 See-Manual references lead the classifier to relevant discussions in the Manual.
11.7 Numbers drawn from Tables 1-6 are prefixed by T1 through T6. (For a complete listing of table names and abbreviations, see paragraph 7.4.)
INTERDISCIPLINARY NUMBERS
11.8 The first class number displayed in an index entry is the number for interdisciplinary works. If the term also appears in a table, the table number is listed separately, along with other aspects of the term. The discipline of the interdisciplinary number may be repeated as a subentry if the discipline is not clear. For example:
Adult education T1—0715
Adult education 374
Adult education—federal aid 379.1215
Adult education—law 344.074
Adult education—public administrative support 353.84
Adult education—public support 379.114
Adult education—public support—law 344.07685
Adult education—special education 371.90475
Adult education—university extension 378.175
11.9 Interdisciplinary numbers are not provided for all topics in the Relative Index. They are omitted when the index entry is ambiguous, does not have a disciplinary focus, or lacks literary warrant. In such cases, there is no entry given for the term without subheadings. For example:
National planning—civic art 711.2
National planning—economics 338.9 (For more information on interdisciplinary numbers, see paragraphs 5.8, 7.16, 7.20-7.21.)
TERMS INCLUDED IN THE RELATIVE INDEX
11.10 The Relative Index contains most terms found in the headings and notes of the schedules and tables, and synonyms and terms with literary warrant for concepts represented by the schedules and tables. The Relative Index also contains terms for the broad concepts covered in Manual notes. Inverted phrases are avoided, except for personal and geographic names (see paragraphs 11.12-11.13). Qualifiers are used for homonyms, ambiguous terms, and most initialisms and abbreviations. The most common use of the term may not be qualified. Disciplinary qualifiers are avoided.
11.11 The following types of names from Table 2 Geographic Areas are included in the Relative Index: (A) names of countries; (B) names of the states and provinces of most countries; (C) names of the counties of the United States; (D) names of capital cities and other important municipalities; and (E) names of certain important geographic features.
11.12 Also included in the Relative Index are the personal names of the following groups of persons: heads of state used to identify historical periods, e.g., Louis XIV; founders or revealers of religions, e.g., Muḥammad; initiators of schools of thought when used to identify the school, e.g., Smith, Adam.
11.13 Place names and other proper names are generally given in the form specified by Resource Description and Access (RDA), based on the names established in the Library of Congress authority files. If the RDA form is not the common English name, an entry is also included under the familiar form of the name. Plants and animals are indexed under their scientific and common names.
11.14 The choice of singular form versus plural form follows ISO 999:1996, Guidelines for the content, organization and presentation of indexes. Count nouns are generally in the plural; noncount nouns and abstract concepts are generally in the singular. Parts of the body are in the plural only when more than one occurs in a fully formed organism (e.g., ears, hands, nose). Plants and animals follow scientific convention in the choice of singular form versus plural form, with the decision based on whether the taxonomic class has more than one member (e.g., Horses, Lion, Lipizzaner horse). Where usage varies across disciplines, the index entry reflects the form preferred in the discipline where interdisciplinary works are classified.
TERMS NOT INCLUDED IN THE RELATIVE INDEX
11.15 Terms usually not included in the print Relative Index are:
(A) Phrases beginning with the adjectival form of countries, languages, nationalities, religions, e.g., English poetry, French cooking, Italian architecture, Hindu prayer books.
(B) Phrases that contain general concepts represented by standard subdivisions such as education, statistics, laboratories, and management; e.g., Art education, Educational statistics, Medical laboratories, Bank management.
When there is strong literary warrant for such a phrase heading as a sought term, it may be included in the Relative Index, e.g., English literature. When the phrase heading is a proper name or provides the only form of access to the topic, it may also be included, e.g., English Channel, French horns, Amharic literature.
Options
12.1 Some devices are required to enable the DDC to serve needs beyond those represented in the standard English-language edition. At a number of places in the schedules and tables, options are provided to give emphasis to an aspect in a library’s collection not given preferred treatment in the standard notation. In some cases, options are also suggested to provide shorter notation for the aspect.
12.2 Options are provided throughout the Classification to emphasize jurisdiction, ethnic or national group, language, topic, or other characteristic.
12.3 Options described in notes appear in parentheses and begin with “Option:”. Options that apply to the full entry appear at the end of the entry; options to a specific instruction in the entry follow the appropriate note. For example, the following option appears at the end of the entry for 420-490: (Option B: To give local emphasis and a shorter number to a specific language, place it first by use of a letter or other symbol, e.g., Arabic language 4A0 [preceding 420], for which the base number is 4A. Option A is described under 410)
12.4 Some optional numbers are enumerated in the schedules and tables and appear in parentheses in the number column. A special optional arrangement (222)-(224) for books of the Bible as arranged in Tanakh appears as a subsection of the Manual note for 221.
12.5 Arrange notes are also options. They represent suggestions only; the material need not be arranged as specified. An example of an arrange note is found at 796.48 Olympic games: “(Option: Arrange specific games chronologically).”
12.6 Some national libraries and central cataloging authorities assign a few optional numbers, e.g., Library and Archives Canada uses C810 for Canadian literature in English and C840 for Canadian literature in French.
12.7 If organization by Indigenous people is preferred over organization by subject, a localoption notation could be formulated by appending Dewey notation for the subject to an alphabetic code representing an Indigenous people. Given the close relationship between peoples and languages, possible sources for the alphabetic code are the ISO 639 Language Codes (parts 1-3 can be searched at https://iso639- 3.sil.org/code_tables/639/read). For example, under such an option, Yupik education could be represented as YPK370.
12.8 Most of the time, the responsibility for implementing an option rests with the local library. Libraries should weigh the value of using an option against the loss in interoperability of numbers. The library will not be able to use numbers assigned by other libraries, and other libraries will not be able to use the optional numbers assigned by the library. In addition, unless the option is widely used in a region, users may be confused by the alternate notation.
Close and Broad Classification
13.1 The Dewey Decimal Classification provides the basic option of close versus broad classification. Close classification means that the content of a work is specified by notation to the fullest extent possible. Broad classification means that the work is placed in a broad class by use of notation that has been logically abridged. For example, a work on French cooking is classed closely at 641.5944 (641.59 Cooking by place + 44 France from Table 2), or broadly at 641.5 (Cooking).
13.2 A library should base its decision on close versus broad classification on the size of its collection and the needs of its users. For example, a work on the sociology of sibling relationships in Canadian society would be most usefully classed in 306.8750971 (306.875 Sibling relationships + 09 Geographic treatment from Table 1 + 71 Canada from Table 2) in a research library or large public library. A small school library might prefer to class the same work in the broader number (306.875) without including the geographic facet in the notation. An engineering library might prefer close classification for works in engineering, but broad classification for disciplines outside science and technology.
13.3 The classifier should never reduce the notation to less than the most specific three-digit number (no matter how small the library’s collection). A number also must never be reduced so that it ends in a 0 anywhere to the right of the decimal point.
13.4 One aid to logical abridgment of DDC numbers is the segmentation device provided by the Decimal Classification Division of the Library of Congress and some other centralized cataloging services.
13.5 Segmentation allows for broad classification of the Dewey Decimal Classification and is intended for use with general collections of 20,000 titles or less. Segmentation marks (indicated by a forward slash in WebDewey) represent the end of the abridged number, providing a logical truncation of the notation and structural hierarchy of the full classification. Some optional numbers have a forward slash before the first number, indicating that they are not used in abridged classification. The class number given before the segmentation mark is used as the complete number for those wishing to use abridged DDC. For example:
004.1/1 Supercomputers
More Information
14.1 Classifiers desiring a more in-depth introduction to the Dewey Decimal Classification may consult Dewey Decimal Classification: Principles and Application, 3d ed., by Lois Mai Chan and Joan S. Mitchell (Dublin, Ohio: OCLC, 2003).
14.2 More information about the use and application of the DDC, plus training materials, can be found on the Dewey web site (http://www.oclc.org/dewey) and on 025.431: The Dewey blog (http://ddc.typepad.com).
Introduction to the Dewey Decimal Classification
- OCLC
- https://www.oclc.org/content/dam/oclc/dewey/versions/print/intro.pdf
- No explicit license information and it is listed on the OCLC website with the title: Resources for teachers and students of the DDC