Open any volume of the Dewey Decimal Classification and you will notice that a class number is rarely just a number and a heading. Tucked beneath many entries are short instructions called notes, and these notes do most of the quiet work of keeping a library consistent. One of the most useful of these is the ‘Class elsewhere’ note. It tells the classifier that a particular topic, even though it may look like it belongs under the current number, actually has a better home somewhere else in the schedules. For students learning document processing, understanding this single note can prevent a surprising number of classification errors.
Table of Contents
- What a ‘class elsewhere’ note actually does
- The core purpose: directing the classifier to a better number
- Examples of ‘class elsewhere’ notes in the schedules
- The ‘medical folklore’ pattern
- Vocational education: a worked entry
- Comparison with ‘class here’ notes
- Class here notes pull topics in
- Class elsewhere notes push topics out
- Why both notes protect against scattering and misplacement
- How these notes fit among the other DDC notes
- A note on careful reading
- Why this matters for real libraries
What a ‘class elsewhere’ note actually does
A ‘class elsewhere’ note is a directional instruction. It appears under a class number and points the classifier away from that number toward a more appropriate one. The note exists because many subjects sit at the boundary between two or more disciplines. Without guidance, two different classifiers could reasonably place the same book in two different numbers. The note removes that guesswork by stating, in plain terms, where a related topic should go instead.
This matters because the DDC is arranged by discipline, not by subject. A single subject can be treated from several angles, and each angle may belong to a different discipline. Clothing, for example, can be studied as psychology, as custom, or as fashion design, and each of these lands in a completely different part of the schedules. ‘Class elsewhere’ notes are the signposts that keep these disciplinary distinctions clear, so that materials end up where users will actually look for them.
The core purpose: directing the classifier to a better number
The essential job of this note is redirection. It does not describe what belongs in the current class. Instead, it identifies what looks like it might belong there but does not, and then names the correct destination. In doing so, the note serves two practical goals. First, it prevents misclassification, the placing of a work in a number that seems intuitive but is technically wrong. Second, it keeps related materials from being scattered across the schedules in a way that would frustrate retrieval.
The official structure of the DDC, maintained today by OCLC, treats these notes as a recognised category of instruction. They are sometimes formally called class-elsewhere notes, and in cataloguing systems they are encoded as a distinct note type so that software and human classifiers read them the same way. The consistency this produces is the whole point. Every library that follows the schedule will route the same topic to the same place.
Examples of ‘class elsewhere’ notes in the schedules
The clearest way to understand these notes is to read real entries from the schedules. Consider the number 791.43, which covers motion pictures. The entry carries an instruction to class the photographic aspects of motion pictures in 778.53, and to class made-for-television movies and videotapes of motion pictures in 791.45. A book about how films are physically shot, focusing on cinematography and photographic technique, therefore does not stay at 791.43. The note sends it to the photography section, because the discipline being treated is photography rather than the motion picture as a public performance.
Another instructive case appears under 791, the number for public performances. Here an exclusion-style instruction makes clear that athletic contests and music performances do not belong, even though both are performed in public. Sports events are routed toward 796, and music performances toward the 780s. The note prevents a classifier from grouping a cricket match, a concert, and a circus together simply because all three happen in front of an audience.
The ‘medical folklore’ pattern
A frequently cited teaching example follows the form “Medical folklore, see 398.353”. Folklore as a subject sits in the 390s, the area of customs, etiquette, and folklore. So when a work deals with traditional or folk beliefs about medicine and healing, the classifier is guided away from the medical sciences in the 610s and toward the folklore number, because the work treats the material as folklore rather than as clinical medicine. This is the ‘class elsewhere’ logic in miniature: the topic mentions medicine, but the discipline being discussed is folklore, so the folklore number wins.
Vocational education: a worked entry
The entry for 370.113, vocational education, shows how several note types work together. The number carries a class-here note grouping career education and occupational training, but it also instructs the classifier to class on-the-job training and vocational training provided by industry in 331.2592, and to send vocational education at the secondary level to 373.246. The class-elsewhere portion does the redirecting. It tells you that although these topics all involve job training, the ones treated as labour economics or as secondary schooling belong in different disciplines and therefore different numbers.
Comparison with ‘class here’ notes
The ‘class elsewhere’ note is best understood next to its counterpart, the ‘class here’ note. The two notes are opposites in function, and reading them together gives the full picture of what a class number contains and what it deliberately excludes.
Class here notes pull topics in
A ‘class here’ note is inclusive. It states that certain topics, including ones broader or narrower than the heading itself, should be placed at that number. For example, under 576 (Microbes), a class-here note directs that works on microbiology be classed at this number, even though microbiology as a field covers more than microbes alone. The effect is to gather related materials together at a single point so that a user browsing the shelf finds them in one place. Class-here notes prevent scattering by actively collecting topics under one number.
Class elsewhere notes push topics out
A ‘class elsewhere’ note does the reverse. It is exclusive in spirit. Rather than gathering topics in, it identifies topics that seem to belong but should be sent away to a more suitable number. Where a class-here note says “this also goes here,” a class-elsewhere note says “this goes there instead.” The two notes are therefore complementary halves of a single boundary-drawing exercise. One defines the inside of a class, the other defines the outside.
The distinction becomes clearer in a side-by-side reading of one entry. At a single class number, a class-here note might confirm that a particular sub-topic stays, while a class-elsewhere note in the same entry confirms that a neighbouring sub-topic leaves. Reading only one of the two notes gives an incomplete instruction. A careful classifier reads both before assigning a number.
Why both notes protect against scattering and misplacement
Both notes exist to solve the same underlying problem from opposite directions: the risk that conceptually related works end up spread across unrelated numbers, or that unrelated works pile up under one number simply because the heading sounds broad. Class-here notes guard against scattering by consolidation. Class-elsewhere notes guard against misclassification by redirection. Together they enforce the discipline-based logic that gives the Dewey Decimal Classification its consistency from one library to the next.
How these notes fit among the other DDC notes
‘Class elsewhere’ notes are one member of a larger family of notes that appear under DDC entries. Alongside them sit inclusion notes, scope or definition notes, ‘class … in …’ notes, and ‘for … see …’ references. Each note type carries a specific kind of instruction, and an experienced classifier learns to read them as a set rather than in isolation. A ‘class elsewhere’ note often works in tandem with a related reference note, the two together describing both the limit of the current class and the path to the correct one.
It is worth distinguishing the ‘class elsewhere’ note from a simple cross-reference. A cross-reference may merely point to a related topic for awareness. A ‘class elsewhere’ note is a firmer instruction. It is telling the classifier that the material in question should not be classed at the current number under the relevant treatment. The wording carries the authority of an instruction, not just a suggestion, which is why following it consistently keeps catalogues across institutions aligned.
A note on careful reading
For students practising document processing, the practical takeaway is simple: never assign a class number from the heading alone. The heading tells you the general territory, but the notes tell you the exact borders. A topic that appears to match a heading may be explicitly sent elsewhere, and missing that instruction is one of the most common reasons two catalogues disagree on where the same book belongs. Reading the full entry, notes included, is the habit that separates a confident classifier from a hesitant one.
Why this matters for real libraries
The value of these notes shows up at the moment a user goes looking for a book. When a reader expects to find works on medical folklore among customs and folklore rather than among clinical medicine, the ‘class elsewhere’ note is the reason the book is actually there. The note converts an abstract rule about disciplines into a concrete shelf location. Multiply this across thousands of boundary topics, and the notes become the connective tissue that makes a large collection navigable.
This also explains why the DDC continues to be revised. As knowledge changes and new boundary topics emerge, the editors add, adjust, and relocate these notes so that the schedule keeps reflecting how subjects are actually treated. A classifier who understands the purpose behind a ‘class elsewhere’ note is therefore not just memorising a number, but reading the reasoning that the system encodes into every entry.
What do you think? When you come across a book that could plausibly sit under two different class numbers, how would you decide which discipline the work is really treating? And can you think of a subject from your own field of study that probably carries a ‘class elsewhere’ note redirecting it somewhere unexpected?
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