On a quarterly basis, we post "Dewey by the Numbers," which gives a snapshot of Dewey’s growth in terms of four types of quantities:
- explicit assignable numbers in the schedules,
- facets (entries in Tables 1–6 or in add tables),
- Relative Index Terms, and
- mapped headings of various stripes.
The 1 March 2016 version of "Dewey by the Numbers" elicited some interesting questions:
- Can you tell whether updates within one edition only contain new numbers, additional notes, comments etc.?
- Or is it possible that an existing number is deleted or changes definition during the same edition of DDC?
- Putting the question another way: If I assigned a DDC number from DDC 23, do I need to consult after each update to make sure that the assigned number still exists with the same meaning like before the update?
Apparently we are really into snapshots. Not only is every "Dewey-by-the-Numbers" table a quantitative snapshot of Dewey at a particular time, but so is a print edition. Although some might think that DDC 23 corresponds to the state of Dewey in 2011, when DDC 23 was printed, to the editorial team, DDC 23 is a living, growing classification system. What the DDC 23 was on 29 February 2016 is not the same as what the DDC 23 was on 1 February 2016. For example, significant changes took place in T2—68 Republic of South Africa and neighboring southern African countries in the interim. (You will be able to find out more about that in a future blog posting.)
What kinds of changes take place in Dewey? Some changes are merely corrections (e.g., deleting an extraneous word, supplying a missing word, correcting typographic errors in words or numbers). But many changes are more substantive. Several Glossary entries explain the types of changes that may be involved:
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.
Relocation: The shifting of a topic from one number to another number that differs from the old number in respects other than length.
Expansion: The development of a class in the schedules or tables to provide further subdivisions.
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.
Schedule reduction: The elimination of certain provisions of a previous edition, often resulting in discontinued numbers.
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.
Now back to those questions. Is it possible that an existing number will be deleted during a single Dewey edition? Yes. All of the topics that were in the number may be discontinued and/or relocated to other numbers, such that a number that was once valid may become obsolete. Is it possible that an existing number will change definition during a single Dewey edition? Unless a complete (or extensive) revision is taking place, it is unlikely that an existing number will completely change its definition, but it is not uncommon for a class to change its definition to some extent during an edition; this may be signaled by new notes, the addition or deletion of topics, etc. (Complete or extensive revisions typically are introduced by a draft for comment posted on the Dewey Discussion Papers page.) Given the types of changes that can take place within a single edition, yes, at least in principle, the classifier should always consult WebDewey to ensure that the meaning of the class has not changed in ways that would now make another number more appropriate.
How can someone know that a change has taken place in a class? Any change visible in the printed version of the class description should be reflected in a PDF posted on the Dewey Updates page. Better yet, a new feature will be coming soon to WebDewey to alert users to changes. (Did you find that tantalizing? You should. But we’re not going to say more about that feature until it’s available.)
How can someone know what change has taken place in a class? Changes on the Dewey Updates page must be discerned by comparing a class description there with the previous class description. In WebDewey, history notes (which the user can choose to display or not, as governed by their preferences) record relocations, expansions, and discontinuations; changes in which topics are in which classes can be seen there. We will be adding more history data later in 2016 to capture some of the topics in relocations, expansions, and discontinuations back to Edition 20 that are now missing. (As before, when that’s available, we’ll say more about it.)