025.431: The Dewey blog

OCLC releases Dewey linked data

OCLC is committed to its linked data strategy, and we continue to publish existing library information as linked data in ways that support better description and discovery of library resources across the web. We’ve already made fundamental steps forward in building a linked data ecosystem with the release of OCLC Meridian and WorldCat Entities. And now, we’re pleased to announce the transformation of another dataset: the Dewey Decimal Classification (DDC) system.   

Unlocking the power of Dewey 

We’re unlocking the power of the DDC to build an increasingly robust linked data infrastructure by creating uniform resource identifiers (URIs) for Dewey numbers. As the foundation for our “concept” entities, this Dewey linked data provides subject classifications to Works entities in WorldCat Entities, creating a layer of new relationships for knowledge graphs that power discovery.  

These identifiers make the Dewey classification numbers more meaningful, create connections between broad classification numbers and specific subject topics, and provide multi-language labels for otherwise opaque numbers. Using machine-actionable and web-friendly URIs, Dewey linked data connects across established classifications and subject headings data. For example, the OCLC Research team mapped Dewey classifications to FAST (Faceted Application of Subject Terminology) topical headings, enabling relationships to the Dewey linked data. 

Who can access Dewey linked data? 

Anyone is free to view and access a base set of Dewey linked data and can begin integrating Dewey URIs into their local data management and discovery systems today.

Libraries that subscribe to WebDewey have access to the full range of Dewey linked data URIs and associated metadata. In addition, two new APIs are available that enable users to easily integrate Dewey linked data into other systems and services. WebDewey users can access these APIs as part of their subscription.

Access Dewey linked data

Find more detail about our linked data strategy at oc.lc/linkeddata.

Learn more about our WebDewey service at oc.lc/webdewey.

Please excuse duplication of this message.

DDC MARC tips: subfields $m and $2

A recent social media discussion asked about the purpose of subfield $m of the MARC 082 field, the field for DDC numbers in the bibliographic format. Subfield $m is a simple binary subfield, in which you can enter a value of a to mark the number as standard or b to mark it as optional.

If you don’t use this subfield, you’re not alone. In a perfect world, it would probably be nice to always have this information specified. But in practice, I think it’s safe to say catalogers are mostly entering standard numbers into the 082 field.

Please do use subfield $m if you’re recording an optional number (so specifically, $m b). If you really want to be thorough, you can use it for standard numbers as well.

Until recently, subfield $m was marked as mandatory on the 082 page in OCLC’s Bibliographic Formats and Standards documentation. We’ve changed that to mark it as optional. If you’re curious, it was probably marked mandatory because it’s marked that way in the Library of Congress’s National Level Requirements. I tip my hat to my OCLC colleague Jay Weitz for tracking that down.

While we’re on the subject of MARC, I wanted to remind you of the changes earlier this year to subfield $2. In short, this subfield now carries date and language information in addition to edition, to give a fuller picture of the provenance of a DDC number. You may have seen examples of this in WorldCat, and as of this writing, the Library of Congress MARC documentation page still has the additions in red text.

If you use a macro or Connexion constant data for subfield $2, you might consider adding $m to it too.

Changes to WebDewey public comments

As the result of recent security enhancements added to WebDewey, HTML markup can no longer be used in comments. The same is true for existing comments. Users who have entered comments with HTML tags should edit their comments and remove the tags.

Remember, there are three levels of comments: personal, institutional, and public. Public comments can be seen by all WebDewey users, and if you delete a public comment, it is deleted for everyone. Please be courteous in your use of comments. You can use the WebDewey preferences to hide personal, institutional, and/or public comments.

Update to WebDewey login process via Connexion

As a result of a security update installed today, users will need to enter their authorization number and password when they launch WebDewey from Connexion (client or browser). You are still welcome to save your WebDewey authorization and password in your web browser to prevent having to enter this information every time.

Brief WebDewey outage August 17

On Tuesday, August 17, we will be doing some brief testing in WebDewey in preparation for its move to HTTPS. The work will start 4:00 PM EDT (8:00 PM UTC) and should not last more than an hour.

While the application may not be entirely inaccessible during this period, disruptions are likely to occur, so I recommend you plan not to use it then.

Update: Testing is complete, and WebDewey has been switched over to HTTPS! Let us know if you have any trouble.

Flash exhibit: Cybercrime

This week, Wired magazine published a fascinating article about Marcus Hutchins, a British hacker who at age 22 foiled the global WannaCry ransomware attack of 2017. Attributed to North Korea, the attack infected out-of-date Windows computers around the world with “ransomware,” a form of malware that locks users out of their data unless they pay a ransom (typically in cryptocurrency) to the hackers. Working from his basement in rural England, Hutchins found a “kill switch” in the malware that rendered it harmless.

Nevertheless, Hutchins was arrested in the United States later the same year, in connection with separate malware he had created in his youth. He had initially worked with malware that infected networks of computers to be used in a distributed denial-of-service (DDoS) attack, which effectively shuts down a website by flooding it with spurious traffic.

In the DDC, computer security threats such as DDoS attacks are classed at 005.87, for computer security threats. See references there draws off malware to 005.88, and computer crimes to 364.168. While comprehensive works on malware are classed at 005.88, one focused on a specific threat such as DDoS attacks stays at 005.87. With today’s flash exhibit, we added new indexing there for distributed denial-of-service attacks, supplementing existing indexing on the broader concept of (non-distributed) denial-of-service attacks.

Moving over to the criminology schedules, we find computer crimes at 364.168 Business, financial, professional offenses, which has computer crime and while collar crime in a class-here note. We added a new index term “Cybercrime”, which previously had no keyword access in WebDewey. We also added a built number, 364.168092, for biography of white collar and computer criminals.

Works on hackers and hacking can ultimately go in either computer science or criminology. Unless you’re working with a very narrow definition, hackers aren’t necessarily criminals to begin with. But what if the choice of number is less obvious? Do a browse search for “Hacking” in the Relative Index:

The base heading shows where the interdisciplinary number is—in this case, computer science. Prefer that number if you don’t have a work of criminology. Everyone is innocent until proven guilty in the DDC!

How many zeros are needed for standard subdivisions?

When you are training new classifiers on WebDewey, do you know a quick way to help them identify how many zeros are needed for standard subdivisions in a specific place, and also help them understand why extra zeros are sometimes needed? In most cases, the short answer is to check the Hierarchy box.

First, let’s review the general instructions. At the start of Table 1 is found this instruction (in WebDewey see the Notes box at T1—0 Table 1. Standard Subdivisions):

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. If the 0 subdivisions of a number in a schedule are used for special purposes, use notation 001-009 for standard subdivisions; if the 00 subdivisions also are used for special purposes, use notation 0001-0009 for standard subdivisions

Similar wording is found in the Introduction (section 8.6).  The statement "If more than one zero is needed, the number of zeros is always indicated in the schedule" means that classifiers need to look in the schedules for patterns to copy. 

In WebDewey, the Hierarchy box is a good place to look for those patterns because it offers a summary of the subdivisions of a number. For example, here is the Hierarchy box for 616 Diseases:

The pattern to follow for standard subdivisions is clear; two zeros are needed:

616.001-616.009 Standard subdivisions

 Why two zeros?  The single-zero subdivisions are used for special purposes, as shown in these entries in the Hierarchy box:

616.02 Special topics of diseases

616.04 Special medical conditions

616.07-616.09 Pathology, psychosomatic medicine, case histories

At 616 Diseases is the class-here note: "Class here clinical medicine, evidence-based medicine, internal medicine." Following the pattern for standard subdivisions shown at 616.001-616.009, we class a work of review and exercise for clinical medicine in 616.0076 (616 + 0 + 076 from T1—076 Review and exercise).

Standard subdivisions are not always labeled "standard subdivisions" when they appear in the schedules; classifiers need to be familiar with the standard subdivisions so that they can recognize notation and captions (including variants of captions) from Table 1 when they see them in the Hierarchy box.  For example, when classifiers see the following in WebDewey: 

They should immediately know that 373.01, 373.02, 373.06, 373.08, and 373.09 are all built with standard subdivisions, because they should recognize T1—01 Philosophy and theory, T1—02 Miscellany, T1—06 Organizations and management, etc. In this Hierarchy box, there are no entries with extra zeros. The pattern shows that a single zero should be used with standard subdivisions. We class a work about urban high schools in 373.091732 (built with 373 + 091 from T1--091 Areas, regions, places in general + 732 from T2--1732 Urban regions).

Another example is the Hierarchy box for 613 Personal health and safety:

Again, there are no entries with extra zeros. The only single-zero subdivision used for special purposes is 613.04 Personal health of people by gender, sex, or age group.  Among the standard subdivisions, T1—04 Special topics is intended to be used only for special purposes.  It has the note: "Use this subdivision only when it is specifically set forth in the schedules." If T1—04 Special topics is the only single-zero subdivision used for special purposes, the rest of the standard subdivisions do not need extra zeros.  The bracketed standard subdivisions—613[.081-613.084] People by gender, sex, or age group—also show the single zero; that record has the do-not-use note: "Do not use; class in 613.04."

The four single-zero subdivisions shown in the Hierarchy box that are marked with orange puzzle pieces are all built with standard subdivisions. The orange puzzle pieces mark these as built numbers that in the print DDC would appear only in the Relative Index; they have index entries serving as captions instead of the standard subdivisions captions that would be used if they were intended to appear in the print schedule:

613.019 Personal health—psychological aspects

613.071 Health—education

613.087 Disabled people—health

613.092 Hygienists

Here are the relevant standard subdivisions:

T1—019 Psychological principles

T1—071 Education

T1—087 People with disabilities and illnesses, gifted people

T1—092 Biography

At 613 Personal health and safety is the standard-subdivisions-are-added note: "Standard subdivisions are added for personal health and safety together, for personal health alone." We class an encyclopedia of personal health in 613.03 (613 + 03 from T1—03 Dictionaries, encyclopedias, concordances).

What if no zero subdivisions are shown in the Hierarchy box?  For example, no zero subdivisions of 613.262 Vegetarian diet are shown in the Hierarchy box:

If no zero subdivisions are shown in the Hierarchy box, and there is no add note in the record, then the general rule applies: "Never use more than one zero in applying a standard subdivision unless instructed to do so." There is no add note in the record for 613.262. Hence we class a history of vegetarian diet in 613.26209 (613.262 + 09 from T1—09 History, geographic treatment, biography).

What if there is an add note in the record?  Then we don’t know how many zeros are needed until we read the add note.  For example, here is the Hierarchy box for 616.723 *Rheumatism:

No zero subdivisions of 616.723 are shown in the Hierarchy box; however, we must consult the Notes box:

The add note is a footnote marked with an asterisk (*):

*Add as instructed under 616.1-616.9

The add note leads to 616.1-616.9 Specific diseases, which has this Hierarchy box:

This hierarchy box first summarizes a large add table, then the other subdivisions under 616.1-616.9.  Each add table entry is shown with 616.1-616.9 plus a colon (:) plus the add table notation and its caption, e.g., 616.1-616.9:001 Philosophy and theory.  The Hierarchy box shows that standard subdivisions require two zeros because the single-zero notation is used for special purposes.  The full add table appears in the Notes box; here is the first part of that large box:

 

 

We class an encyclopedia of rheumatology in 616.723003 (616.723 + 0 + 03 from T1—03 Dictionaries, encyclopedias, concordances).

For special instructions on using the WebDewey number building tool to add standard subdivisions to three-digit numbers ending in zero, see these previous posts: part 1, part 2.

In some cases it is not easy to show patterns for standard subdivisions, and instead special instructions are given in add notes. In those cases—unless there happens to be a built number that shows the pattern—the Hierarchy box is not particularly helpful; classifiers must rely on the add notes. An example can be found at 337.3-337.9 Foreign economic policies and relations of specific jurisdictions and groups of jurisdictions.  Here is the Hierarchy box:

Here are the relevant add notes from the Notes box:

Add to base number 337 notation T2—3-T2—9 from Table 2, e.g., economic policy of United Kingdom 337.41; then, for foreign economic relations between two jurisdictions or groups of jurisdictions, add 0* and to the result add notation T2—1-T2—9 from Table 2, e.g., economic relations between United Kingdom and France 337.41044

*Add 00 for standard subdivisions; see instructions at beginning of T1—0

The main add note shows how the single-zero subdivisions are used for a special purpose—to show foreign economic relations between two jurisdictions or groups of jurisdictions—and the footnote marked with an asterisk (*) indicates that when only one jurisdiction or group of jurisdictions is specified and then a standard subdivision is added, two zeros are needed.  A history of United States foreign economic relations is classed in 337.73009 (337 + 73 from T2—73 United States + 0 + 09 from T1—09 History, geographic treatment, biography).

At the start of Table 5—at T5—0 Table 5. Ethnic and National Groups in WebDewey—are special instructions.  Here are key portions copied from the Notes box:

Except where instructed otherwise, and unless it is redundant, add 0 to the number from this table and to the result add notation T2—1 or T2—3-T2—9 from Table 2 for area in which a group is or was located, e.g., Germans in Brazil T5—31081, but Germans in Germany T5—31; Jews in Germany or Jews from Germany T5—924043. If notation from Table 2 is not added, use 00 for standard subdivisions; see below for complete instructions on using standard subdivisions

. . . .

When Table 5 notation is not followed by 0 plus notation from Table 2, use 00 for standard subdivisions, e.g., periodicals about sociology of Japanese 305.8956005, collected biography of Irish Americans in New York City 974.71004916200922. When Table 5 notation is followed by 0 plus notation from Table 2, however, use 0 for standard subdivisions, e.g., periodicals about sociology of Japanese Americans 305.895607305. (For the purpose of this rule, notation T5—96073 African Americans is treated as Table 5 notation, e.g., periodicals on sociology of African Americans 305.896073005, periodicals on sociology of African Americans in Ohio 305.896073077105) 

Classifiers need to be aware of the instructions at the start of Table 5 when adding notation from Table 5, because those instructions are not repeated in the schedules where add notes say to add notation from Table 5.   

Is This All They Have? Part 3

A previous post introduced the possibility of using DDC-based signage and QR codes to help patrons find works on the same phenomenon but from a different disciplinary perspective.  The post also issued an invitation for a few libraries to participate in a pilot project to evaluate the usefulness of such signage.  (See the post on “requirements” for participating in the pilot project.)  In the meantime, we share a few additional QR codes we suspect some users might find useful.

Imagine a patron looking at the materials on postal service in 383.  Would the following signage help?

Or imagine a patron looking at the materials on sports in 796.  Would the following signage help? 

DDC-Based Signage and QR Codes Pilot Project: What's Needed from You

A previous post introduced the possibility of using DDC-based signage and QR codes to help patrons find works on the same phenomenon but from a different disciplinary perspective.  The post also issued an invitation for a few libraries to participate in a pilot project to evaluate the usefulness of such signage. 

We have been asked what the requirements are for participating in the pilot project.  Here’s our sense:

1. You need to have a collection shelved by DDC numbers

2. You need to have an OPAC that can be searched by call number (Note 1. Sometimes such a search is possible, even if it isn’t advertised to users.  Note 2. Of course you want users to be able to read the search results on their mobile device.)

3. You need buy-in from colleagues and the powers-that-be to put up signage in your stacks

4. You need to be willing to scan two documents we have put together of (a focused subset of) DDC numbers that are related by see or see-also references and to identify which links to related numbers and subjects make most sense for your patrons (Note. If your DDC number usage is not aligned with DDC 23, you may need to make some modifications in the relationships shown.)

5. You need to determine what you want your signage to look like and will be responsible for its production (we can give you some guidance, if needed, on how to produce the QR codes)

6. We would ask that you gather patron comments about the signage—what works, what doesn’t work, what can be improved, etc.—to share with us so we can share with others

7. If the signage is helpful to your patrons, we would love for you to promote this search enhancement through whatever channels make sense

There is no need for all the libraries in the pilot to stick to the same schedule, so we invite you to join the pilot whenever the time is right for you!

Is This All They Have?

How often do your patrons (1) find a set of resources in the collection that are relevant (or maybe only semi-relevant) to their interests, but (2) end up wondering if there are other relevant (or more relevant) resources somewhere else in the collection?  The disciplinary basis of Dewey has as an intended consequence that works about the same phenomena may be located at different places in the classification system.  Shelving materials by DDC notation will then cause resources on the same phenomena to be subject to some degree of physical scatter as well.  While sophisticated users will appreciate the attendant disciplinary context and specificity that this provides, more casual users may not. 

Is there some way to cater to disciplinary and phenomenon perspectives simultaneously?  The DDC offers several tools that facilitate finding where phenomena are treated from different perspectives.  The Relative Index is one such tool; see and see-also references in the schedules are other such tools.  “Get real!” we hear you saying.  “We don’t make copies of the DDC / access to WebDewey available to our users.  Besides, how many of them would even be interested?” 

Ah, but what if you (with a little help from your friends, that is, us) were to identify the relationships found in the Relative Index and/or see or see-also references that are most important to your users and display them as signage in your collection?  And if you have an OPAC that is searchable by DDC number, what if your signage were to include a QR code that let users immediately see what you have at other locations in the collection?

For example, let’s say you have a patron looking at the materials on retirement at 306.38.  S/he wonders, “Is this all they have?”  And then they notice nearby something like the following:

Go ahead—whip out your cell phone and scan away.  Nifty, huh?  (Of course, the actual results would reflect the holdings of your institution and how search results from your OPAC display on a mobile device.)

We are interested in working with a few libraries who would be interested in piloting such a signage program based on relationships in the DDC.  If you are interested, please email me (Rebecca Green) at [email protected] (“DDC signage pilot” in your subject line would be a great help).  Meanwhile we will periodically present other DDC-based relationships and associated QR codes as enticements.  (Our thanks to Christine Burroughs, who helped us think through the possibilities here while she was at Shaker Heights Public Library.)