Dewey Decimal Classification glossary

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A

Abridged edition
A shortened version of the Dewey Decimal Classification (DDC) system that is a logical truncation of the notational and structural hierarchy of the corresponding full edition on which it is based. The abridged edition is intended for general collections of 20,000 titles or less. See also broad classification; Full edition.

Add note
A note instructing the classifier to append digits found elsewhere in the DDC to a given base number. See Base number.

Add table
See Tables (2).

Application
See Rule of application.

Approximate the whole
When a topic is nearly coextensive with the full meaning of a DDC class, the topic is said to "approximate the whole" of the class. The term is also used to characterize topics that cover more than half the content of a class. When a topic approximates the whole of a class, standard subdivisions may be added. Topics that do not approximate the whole are said to be in "standing room" in the number. See also Class-here note; Standard-subdivisions-are-added note; Standing room.

Area table
An auxiliary table (Table 2) that gives geographic areas primarily, but also lists historical periods and several numbers for persons associated with a subject. Areas of the world are listed systematically, not alphabetically. Area table notation may be used with other numbers in the schedules and tables when explicit instructions permitting such use are given. See also Tables.

Arrange-alphabetically note
A note suggesting the option of alphabetical subarrangement when identification by specific name or other identifying characteristic is desired. See also Option.

Arrange-chronologically note
A note suggesting the option of chronological subarrangement when identification by date is desired. See also Option.

Artificial digit
A letter or other symbol used optionally as a substitute for digits 0–9 to provide a more prominent location or shorter notation for a jurisdiction, language, literature, religion, ethnic or national group or other characteristic. See also Option.

Aspect
An approach to a subject or characteristic (facet) of a subject. See also Discipline; Facet; subject.

Attraction
See Classification by attraction.

Author number
See Book number.
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B

Base number
A number of any length to which other numbers are appended. See also Add note.

Book number
The part of a call number that distinguishes a specific item from other items within the same class number, also called a Cutter number. A book number is composed of letters from the author's name or letters from the title main entry and numbers. There are several systems for creating book numbers.
A library using the Cutter-Sanborn system can have D548d indicate David Copperfield by Dickens (where D stands for the D of Dickens, 548 stands for "ickens" and d stands for David Copperfield). See also call number; Cutter number; Work mark.

broad classification
The classification of works in broad categories by logical abridgment, even when more specific numbers are available, e.g., the use of 641.5 Cooking instead of 641.5972 Mexican cooking for a cookbook of Mexican recipes. Broad classification is the opposite of close classification. See also Abridged edition; Close classification.

Built number
A number constructed according to add instructions stated or implied in the schedules or tables. See also Number building.
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C

call number
A set of letters, numerals or other symbols (in combination or alone) used by a library to identify a specific copy of a work. A call number consists of the class number and book number (or Cutter number).
It may also contain other data such as date, volume number, copy number and location symbol. See also Book number.

Caption
See Heading.

Category
See Class (Noun:).

centered entry
An entry representing a subject covered by a span of numbers, e.g., 372–374 Specific levels of education. The entry is called "centered" because the span of numbers appears in the center of the page in the print version of the DDC rather than in the number column on the left side of the page. Centered entries are identified by the symbol > in the number column.

Characteristic of division
See Facet.

Citation order
The order in which two or more characteristics (facets) of a class are to be combined in number building. When number building is not permitted or possible, instructions on preference order with respect to the choice of facets are provided. See also Facet.; Number building; Preference order.

Class
Noun: (1) A group of objects exhibiting one or more common characteristics, identified by specific notation. See also Entry. (2) One of the ten major groups of the DDC numbered 0–9. See also Main class. (3) A subdivision of the DDC of any degree of specificity. See also Subdivision.

Verb: To assign a class number to an individual work. See also classify.

Class-elsewhere note
A note instructing the classifier about the location of interrelated topics. The note may show preference order, lead to the interdisciplinary or comprehensive number, override the first-of-two rule or lead to broader or narrower numbers in the same hierarchical array that might otherwise be overlooked. See also Comprehensive number; Interdisciplinary number; Preference order.

Class-here note
A note that identifies topics that are equivalent to the whole of the class under which the note appears. The topic as a whole is classed in the number under which the note appears; parts of the topic are classed in the most appropriate subdivision of the number. Topics identified in class-here notes, even if broader or narrower than the heading, are said to "approximate the whole" of the number; therefore, standard subdivisions may be added for topics in class-here notes. Class-here notes also may identify the comprehensive or interdisciplinary number for a subject. See also Approximate the whole; Comprehensive number; Interdisciplinary number.

classification
A logical system for the arrangement of knowledge, including notations for identifying where in a classification a given item belongs.

Classification by attraction
The classification of a specific aspect of a subject in an inappropriate discipline, usually because the subject is named in the inappropriate discipline but not mentioned explicitly in the appropriate discipline.

classify
(1) To arrange a collection of items according to a classification system. (2) To assign a classification number to an individual work.

Close classification
The classification of works to the fullest extent permitted by the notation. Close classification is the opposite of broad classification. See also broad classification; Full edition.

Coextensive
Describes a topic equal in scope to the concept represented by the number.

Comparative table
A table provided for a complete or extensive revision that lists in alphabetical order selected topics accompanied by their previous number and their number in the current edition. See also Equivalence table; Revision.

Complete revision
See Revision ( Complete revision).

Complex subject
A complex subject is a subject that has more than one characteristic. For example, "unemployed carpenters" is a complex subject because it has more than one characteristic (employment status and occupation). See also Preference order.

Comprehensive number
A number (often identified by a "Class here comprehensive works" note) that covers all the components of the subject treated within that discipline. The components may be in a span of consecutive numbers or distributed throughout the schedule or table. See also Interdisciplinary number.

Coordinate
Describes a number or topic at a level equal to another number or topic in the same hierarchy.

Cross classification
The accidental placement of works on the same subject in two different class numbers. This tends to happen when works being classified deal with two or more characteristics of a subject in the same class. Notes on preference order should prevent cross classification. See also Preference order.

Cross reference
See Class-elsewhere note; See reference; See-also reference.

CSD
See OCLC Customer Services Division (CSD).

Cutter number
A book number based on the widely used scheme devised by Charles Ammi Cutter. In colloquial usage, synonymous with book number. See Book number.
More specifically, the notation in a book number derived from the Cutter Three-Figure Author Table, the Cutter-Sanborn Three-Figure Author Table, or the OCLC Four-Figure Cutter Tables. The OCLC Four-Figure Cutter Tables are revised and expanded versions of the Cutter Three-Figure Author Table and the Cutter-Sanborn Three-Figure Author Table. WorldCat Cataloging Partners assigns Cutter numbers the same way the Cutter macro creates Cutter numbers. See also Book number.
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D

DDC Summaries
A listing of the first three levels (main classes, divisions and sections) of the Dewey Decimal Classification system. The headings associated with the numbers in the summaries have been edited for browsing purposes and may not match the complete headings found in the schedules. See also Division; Main class; Section; Summary.

Decimal point
The dot that follows the third digit in a DDC number. In strict usage the word "decimal" is not accurate; however, common usage is followed in this edition's explanatory material.

Definition note
A note indicating the meaning of a term in the heading.

Dewey Services Only session
A Connexion session that provides access to WebDewey and/or Abridged WebDewey. A Dewey Services Only session: does not incur access and user support fees; does not count against simultaneous logon limits for libraries subscribing to flat fee Internet or dedicated TCP/IP access; and includes a default inactivity timeout of 120 minutes (default timeout for other Connexion sessions is 40 minutes). Authorized users can start a Dewey Services Only session from the Connexion logon screen or from within an active Connexion cataloging session.

digit
The smallest individual unit in a notational system. For example, the notation 954 has three digits: 9, 5 and 4.

Discipline
An organized field of study or branch of knowledge, e.g., 200 Religion, 530 Physics, 364 Criminology. In the Dewey Decimal Classification, subjects are arranged by disciplines. See also subject.

Discontinuation
The shifting of a topic or the entire contents of a number to a more general number in the same hierarchy or the complete removal of the topic or number. A topic or number is discontinued because the topic or concept represented by the number has a negligible current literature or represents a distinction that is no longer valid in the literature or common perception of the field. A note explaining its shift or removal accompanies a discontinued topic or number. Discontinued numbers appear in square brackets. See also Relocation; Schedule reduction.

Displaced standard subdivision
A standard subdivision concept given special notation in the schedule in place of its regular notation from Table 1. A do-not-use note is always provided at the regular location of the standard subdivision concept. See also Do-not-use note; Standard subdivisions.

Division
The second level of subdivision in the DDC, represented by the first two digits in the notation, e.g., 62 in 620 Engineering and allied operations. See also DDC Summaries; Main class; Section.

Do-not-use note
A note instructing the classifier not to use all or part of a regular standard subdivision notation or an add table provision, but instead to use a special provision or standard subdivision notation at a broader number. See also Displaced standard subdivision.

Document
A generic term for all media capable of conveying, coding and preserving knowledge. Documents may be books, journals, electronic resources, reports, sound recordings, motion pictures, etc.

Dual heading
A heading with two separate terms, the first of which is the main topic and the second of which is a major subordinate topic, e.g., 570 Life sciences    Biology. A dual heading is used when the subject as a whole and the subordinate topic as a whole share the same number and most of its subdivisions. Standard subdivisions may be added for either or both topics in a dual heading.

Dual provision
The inadvertent provision of more than one place in the DDC for the same aspect of a subject.
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E

Entry
(1) In the schedules and tables, a self-contained unit consisting of a number or span of numbers, a heading and often one or more notes. (2) In the Relative Index, a term or phrase usually followed by a DDC number. (3) In the Manual, a self-contained unit consisting of a number or group of numbers, the associated headings or topics and an extended instruction or discussion.

Enumerative scheme
A classification system in which numbers for complex subjects are precombined and listed.

Equivalence table
A table provided for a complete or extensive revision that lists in numerical order the classes of the current edition with their equivalent numbers in the previous edition (and vice versa). See also Revision.

Expansion
The development of a class in the schedules or tables to provide further subdivisions. See also Revision.

Extensive revision
See Revision ( Extensive revision).
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F

Facet
Any of the various categories into which a given class may be divided, e.g., division of the class "people" into the categories of ethnicity, age, education and language spoken. Each category contains terms based on a single characteristic of division, e.g., children, adolescents and adults are characteristics of division of the "ages" category. See also Citation order.

Facet indicator
A digit used to introduce notation representing a characteristic of the subject. For example, "0" is often used as a facet indicator to introduce standard subdivision concepts.

First-of-two rule
The rule instructing that works dealing equally with two subjects that are not used to introduce or explain one another are classed in the number coming first in the schedules or tables.

Footnote
An instruction that applies to many subdivisions of a class or to a topic within a class. The affected subdivision or topic is marked with a symbol such as an asterisk. In the print version of the DDC, the footnote is located at the bottom of the page. In the electronic version, the footnote is included in the notes section of each class to which the instruction applies.

Former-heading note
A note listing the heading associated with the class number in the previous edition. The note is used when the heading has changed so much that it bears little or no resemblance to the previous heading, even though the meaning of the number has remained substantially the same.

Full edition
The complete version of the Dewey Decimal Classification (DDC) system. See also Abridged edition.; Close classification.
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H

Heading
The word or phrase used as the description of a given class. Also called "caption."

Hierarchical force
The principle that the attributes of a class as defined in the heading and in certain basic notes apply to all the subdivisions of the class and to all other classes to which reference is made.

Hierarchy
The arrangement of a classification system from general to specific. In the DDC, the length of the notation and the corresponding depth of indention of the heading usually indicate the degree of specificity of a class. Hierarchy may also be indicated by special headings, notes and centered entries.

Hook number
A number in the DDC without meaning in itself, but used to introduce examples of the topic. Hook numbers have headings that begin with "Miscellaneous," "Specific" or "Other" and do not contain add notes, including notes or class-here notes. Standard subdivisions are always bracketed under hook numbers.
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I

Including note
A note enumerating topics that are logically part of the class but are less extensive in scope than the concept represented by the class number. These topics do not have enough literature to warrant their own number. Standard subdivisions may not be added to the numbers for these topics. See also Literary warrant; Standing room.

Indention
Typographical setting of notes and subheadings below and to the right of the main entry term.

Influence
See Rule of application.

Interdisciplinary number
A number (often identified by a "Class here interdisciplinary works" note) to be used for works covering a subject from the perspective of more than one discipline, including the discipline where the interdisciplinary number is located, e.g., the interdisciplinary number for marriage is 306.81 in Sociology. See also Comprehensive number.
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L

Literary form
A mode of literary expression such as poetry, drama, fiction, etc. Each form can be subdivided into kinds of forms, e.g., lyric poetry, comedy, science fiction, etc.

Literary warrant
Justification for the development of a class or the explicit inclusion of a topic in the schedules, tables or Relative Index, based on the existence of a body of literature on the topic.
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M

Main class
One of the ten major subdivisions of the DDC, represented by the first digit in the notation, e.g., 3 in 300 Social sciences.
See also DDC Summaries; Division; Section.

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. In the schedules and tables, see-Manual references indicate where relevant discussions are located in the Manual. See also Manual note.

Manual note
An individual entry in the Manual. See also Entry (3); Manual; See-Manual reference.
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N

Notation
Numerals, letters and/or symbols used to represent the main and subordinate divisions of a classification scheme. In the DDC, Arabic numerals are used to represent the classes, e.g., notation 07 from Table 1 and 511.3 from the schedules.

Notational synthesis
See Number building.

Note
An instruction, definition or reference that explains the contents and use of a class, or the relationship of the class to other classes. See also Add note; Arrange-alphabetically note; Arrange-chronologically note; Class-elsewhere note; Class-here note; Definition note; Discontinuation; Do-not-use note; Footnote; Former-heading note; Including note; Manual note; Number-built note; Preference order; Relocation; Revision note; Scope note; See-also reference; See-Manual reference; See reference; Standard-subdivisions-are-added note; Subdivisions-are-added note.

Number building
The process of constructing a number by adding notation from the tables or other parts of the schedules to a base number. See also Base number; Citation order.

Number-building note
See Add note.

Number-built note
A note that states where the number building instructions may be found for a built number that is explicitly listed in the schedules or tables. Typically, such built numbers are listed for two reasons: to provide an entry for a built number under which other notes are required or to provide an entry for a three-digit built number.

Number column
In the print version of the DDC, the column of numbers that appears in the left margin of the schedules and tables and to the right of the alphabetical entries in the Relative Index.
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O

OCLC
Previously called Online Computer Library Center, Inc. and Ohio College Library Center. Nonprofit membership organization serving libraries around the world to further access to the world's information and reduce library costs by offering services for libraries and their users.

OCLC Customer Services Division (CSD)
OCLC's user assistance and support contact desk that provides support for telecommunications, hardware, and software. Formerly called OCLC User and Network Support (UNS).

OCLC User and Network Support (UNS)
See OCLC Customer Services Division (CSD).

Option
An alternative to standard notation provided in the schedules and tables to give emphasis to an aspect in a library's collection not given preferred treatment in the standard notation. In some cases, an option may provide shorter notation for the aspect. See also Optional number.

Optional number
(1) A number listed in parentheses in the schedules or tables that is an alternative to the standard notation. (2) A number constructed by following an option. See also Option.

Order of preference
See Preference order.
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P

Period table
A table giving chronological time periods with their notation. For many literatures, period tables are given in the schedules. For works not limited to a particular language, the period notation is taken from Table 1 –0901–0905. See also Tables.

Phoenix schedule
See Revision ( Complete revision).

Preference order
Indicates which one of two or more numbers is to be chosen when different characteristics of a subject cannot be shown in full by number building. A note (sometimes containing a table of preference) indicates which characteristic is to be selected for works covering more than one characteristic. When a notation can be synthesized to show two or more characteristics, it is a matter of citation order. See also Citation order.

Preference table
See Preference order.

Prime marks
See Segmentation.
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R

Reduction of schedules
See Schedule reduction.

Regularization
The replacement of special developments for standard subdivision concepts by use of the regular standard subdivisions found in Table 1.

Relative Index
The index to the DDC. It is called "Relative" because it shows the connection between subjects and the disciplines in which they appear. In the schedules, subjects are arranged within disciplines. In the Relative Index, subjects are listed alphabetically. Under each subject, the disciplines in which the subject is found are listed alphabetically. In the print version of the DDC, the disciplines are indented under the subject. In the electronic version, the disciplines appear as subheadings associated with the subject.

Relocation
The shifting of a topic from one number to another number that differs from the old number in respects other than length. Notes at both ends of the relocation identify the new and former numbers. See also Discontinuation.

Retroactive citation order
In number building, the combination of characteristics (facets) of a class starting with a number coming later in the schedule as the base number, then adding as instructed from numbers earlier in the sequence.

Reused number
A number with a total change in meaning from one edition to another. Usually numbers are reused only in complete revisions or when the reused number has been vacant for two consecutive editions.

Revision
The result of editorial work that alters the text of any class of the DDC. There are three degrees of revision: Routine revision is limited to updating terminology, clarifying notes and providing modest expansions. Extensive revision involves a major reworking of subdivisions but leaves the main outline of the schedule intact. Complete revision (formerly called a phoenix) is a new development; the base number remains unchanged from the previous edition, but virtually all subdivisions are changed. Changes for complete and extensive revisions are shown through comparative and equivalence tables rather than through relocation notes in the schedule or table affected. See also Comparative table; Equivalence table.

Revision note
A note that introduces a complete or extensive revision.

Routine revision
See Revision. (Routine revision).

Rule of application
The rule instructing that works about the application of one subject to a second subject or the influence of one subject on another subject are classified with the second subject.

Rule of three
The rule instructing that works giving equal treatment to three or more subjects that are all subdivisions of a broader subject are classified in the first higher number that includes all of them.

Rule of zero
The rule instructing that subdivisions beginning with zero should be avoided if there is a choice between the 0 subdivision and subdivisions beginning with 1–9 in the same position in the notation. Similarly, subdivisions beginning with 00 should be avoided when there is a choice between 00 and 0.
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S

Scatter note
A class-elsewhere, see-reference or relocation note that leads to multiple locations in the DDC. See also Class-elsewhere note; Relocation; See reference.

Schedule reduction
The elimination of certain provisions of a previous edition, often resulting in discontinued numbers. See also Discontinuation.

Schedules

(1) Listings of subjects and their subdivisions arranged in a systematic order with notation given for each subject and its subdivisions. (2) The series of DDC numbers 000–999, their headings and notes.

Scope note
A note indicating that the meaning of a class number is broader or narrower than is apparent from the heading.

Section
The third level of subdivision in the DDC, represented by the first three digits in the notation, e.g., 641 in 641 Food and drink. DDC Summaries; Division; Main class.

See-also reference

(1) In the schedules and tables, a note leading to classes that are tangentially related to the topic and therefore might be confused with it. (2) In the Relative Index, a note leading to a synonym, broader term or related term. (3) In the Manual, a note leading to related Manual notes.

See-Manual reference
A note leading from an entry in the schedules or tables to additional information about the number in the Manual.

See reference
A note (introduced by the word "for") that leads from the stated or implied comprehensive or interdisciplinary number for a subject to component parts of the subject in numbers other than direct subdivisions of the original number or span. See also Class-elsewhere note.

Segmentation
The indication of logical breaks in a number by a typographical device, e.g., slash marks or prime marks. Segmentation marks indicate the end of an abridged number or the beginning of a standard subdivision.

Shelf mark
See call number.

Standard subdivisions
Subdivisions found in Table 1 that represent frequently recurring physical forms (dictionaries, periodicals) or approaches (history, research) applicable to any subject or discipline. They may be used with any number in the schedules and tables for topics that approximate the whole of the number unless there are instructions to the contrary. See also Tables.

Standard-subdivisions-are-added note
A note indicating which topics in a multiterm heading may have standard subdivisions added to them. The designated topics are considered to approximate the whole of the number. See also Approximate the whole.

Standing room
A term characterizing a topic without sufficient literature to have its own number, and considerably narrower in scope than the class number in which it is included. Standard subdivisions cannot be added to a topic in standing room, nor are other number-building techniques allowed. Topics listed in including notes have standing room in the class number, as do minor unnamed topics that logically fall in the same place in the DDC. To have standing room is the opposite of approximating the whole. See also Approximate the whole.

Subdivision
(1) A subordinate member of a class, e.g., 519 Probabilities and applied mathematics is a subdivision of class 510 Mathematics and 519.3 Game theory is a subdivision of 519. See also Class (3). (2) Notation that may be added to other numbers to make a class number appropriately specific to the work being classified. See also Standard subdivisions; Tables.

Subdivisions-are-added note
A note used where subdivisions are provided by adding instructions indicating which topics in a multiterm heading may have subdivisions added to them. The designated topics are considered to approximate the whole of the number. See also Approximate the whole.

subject
An object of study. Also called topic. A subject may be a person or a group of persons, thing, place, process, activity, abstraction or any combination of these.

Also, a content designator or topic. Subject schemes (for example, Library of Congress Subject Headings (LCSH)) use a controlled vocabulary to categorize library materials about the same subject.

In the Dewey Decimal Classification, subjects are arranged by disciplines. A subject is often studied in more than one discipline, e.g., marriage is studied in several disciplines such as ethics, religion, sociology and law. See also Discipline.

Subject catalog
An index to the contents of a collection. If access is provided alphabetically by words, it is called an alphabetical subject catalog. If access is provided by the notation of a classification system, it is called a classified catalog.

Subordinate
Describes a number or topic at a lower (narrower) level than another number or topic in the same hierarchy. See also Superordinate.

Summary
A listing of the chief subdivisions of a class that provides an overview of its structure. See also DDC Summaries.

Superordinate
Describes a number or topic at a higher (broader) level than another number or topic in the same hierarchy. See also Subordinate.

Synthesis of notation
See Number building.
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T

Table of preference
See Preference order.

Tables
In the DDC, lists of notation that may be added to other numbers to make a class number appropriately specific to the work being classified. The numbers found in a table are never used alone. There are two kinds of tables: (1) The numbered auxiliary tables (Tables 1–6; in the Abridged Edition, Tables 1–4) representing standard subdivisions, geographic areas, aspects of literature and languages, ethnic groups, etc. (2) Lists of special notation found in add notes under specific numbers throughout the schedules and occasionally in Tables 1–6. These lists are called add tables. See also Add note.

Topic
See subject.
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U

unabridged edition
See Full edition.

UNS
See OCLC Customer Services Division (CSD).
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V

Variant-name note
A note listing synonyms or near synonyms for a topic in a heading when it is awkward or inappropriate to include such information in the heading.
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W

word-by-word alphabetization
Refers to the filing of entries word by word, not letter by letter. For example, New York files before Newark in word-by-word alphabetization; Newark files before New York in letter-by-letter alphabetization.

Work
A distinct intellectual or artistic expression.

work mark
The part of a book number that consists of a letter appended to the author (or biographer) designation to show the first letter of the title (or first letter of the surname of the biographer). See also Book number.