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Picturing Classification The Evolution and Use of Alternative Classification in Dutch Public Libraries

by Rachel Ivy Clarke, raclarke@uw.edu on May 7, 2013

Libraries, especially public libraries, have been enthralled with decimal classification systems since Dewey’s flash of inspiration at the end of the nineteenth century. His genius invention—to classify library materials using a subject-based decimal notation system—allowed for an extensible interfiling of library materials previously unknown. Decimal-based classification notation is brief, expressive, and hospitable, making it ideal not only for the basis of the Dewey Decimal Classification (DDC), but many other classification systems throughout the world. Many European countries, the Netherlands among them, created library classification systems based on this concept, which have been as ubiquitous to libraries as buns and glasses are to librarians.

Until recently, that is, when some librarians began to voice their concerns about their patrons’ abilities to efficiently and effectively navigate decimal-based organization systems. In America, Maricopa County (Ariz.) Libraries traded in DDC for BISAC (Book Industry Standards and Communications), a keyword-based system used by the commercial book industry, to offer patrons the parallel experience of a familiar bookstore. The Markham Public Library (Ontario, Canada) developed an entirely new local system, still numerical, but based on local library customer needs and wants.

A decade earlier, the Netherlands struggled with similar issues. The traditional system, SISO (a decimal-based system similar to DDC) was perceived as too difficult for children—even for some adults. Many individual libraries took it upon themselves to develop “audience-friendly” alternatives to SISO that used “everyday language,”1 but these were quite specific to each institution. As more and more libraries implemented unique alternative schemes, the differences among these schemes became problematic. Classifications varied from library to library, confusing users. Local librarians had to maintain their home-grown systems and reclassify all their acquisitions accordingly. These libraries needed a system that was straightforward for patrons to use—especially patrons who don’t use the library catalog—both within individual libraries as well as across the country. Libraries cried out for a centralized classification system that would be universally applicable, easy for patrons to use and for librarians to apply.

In 1998, NBD Biblion took up the call. NBD Biblion is a national centralized library service agency which provides a variety of products and services, including acquisitions, bibliographic description/cataloging, binding, classification labeling, RFID/security, and more, to all types of libraries in the Netherlands.2 NBD Biblion was originally formed by libraries, with librarians filling the board of directors. The organization is not government funded and so runs under a business model to continue offering services to libraries.

NBD Biblion began by sending representatives to tour the country and examine many of the locally developed systems, trying to glean the advantages from each one. First, they considered the idea of classification using color alone, but that was limited in many ways, mostly a lack of accommodation for colorblind patrons. Then they considered using keywords alone. Eventually, they drew ideas from all of these systems. They modeled the new nonfiction classification on a system previously designed by NBD Biblion to organize fiction by genre, where each genre is identified by a representative symbol, or pictogram, printed on the spine label of the book along with the first four letters of the author’s name (see figure 1).

The new system for nonfiction, PIM, uses a combination of color-coded pictograms and keywords to organize physical nonfiction library materials. PIM is designed to “speak for itself,” said Erwin Tuinstra, editor of subject indexing at NBD Biblion who oversees PIM.3 Unlike decimal-based systems, which essentially translate subjects into numerals, PIM clearly demonstrates the subject matter embodied in the materials. Tuinstra emphasized that PIM is specifically intended for library patrons who don’t use the library catalog or who are more inclined to browse rather than search for specific materials. Combined with wayfinding signage and innovative shelf labeling, he said PIM is designed to “show its own way” around the library without the need to rely on a catalog search or reference inquiry.4

How It Works

PIM is an alphabetically based system with two main parts: categories and keywords.5 Spine labels for books and other materials include both of these components, as well as the first four letters of the main entry (see figure 2).

Items are grouped first by category, which is represented by a color-coded symbol, one of twenty-seven pictograms grouped into color families (see figure 3). While there is no “name” for the overarching color-coded areas, each color clearly represents a topical area: red represents the area of the arts, blue for geography and history, orange for leisure activities like hobbies and sports, and so forth.6 Within each general pictogram category, items are assigned more specific subject keywords.

Within a library, items are grouped first by the pictograms and then arranged alphabetically by keyword. PIM has no prescribed order other than this alphabetical arrangement within categories. It is purposefully designed to be a flexible system in which local libraries can “easily make changes without prejudice to the national system.”7 Libraries may arrange sections in whatever order best suits their needs. So a library with a large arts section may choose to place that first in the shelf order, while a library with a collection heavy in history may emphasize that class. Some libraries may alphabetize by author or main entry within keyword sections, while other libraries forego this step. Since their patrons do not seem to utilize the alphabetical-by-author organization, these libraries save time shelving materials. Shelf labels and signage are used to navigate within a particular library rather than relying on a preset ordering system like those inherent in decimal or alphanumeric systems. Additionally, if a material is pre-assigned a PIM category that does not match the local view of how it should be categorized, it can easily be classified according to the local view without affecting the overall system.


To develop the pictograms, sample symbols were shown to a test group of approximately 1,000 people, representing both librarians and patrons. Participants were shown a symbol and asked what the symbol made them think of, in order to see if the pictogram clearly expressed the intended meaning. After finalizing the symbols, a later study presented potential patrons and librarians with “dummy” books, mocked up with sample labels, for feedback.

The keywords used in PIM are derived from the Dutch NBD Biblion thesaurus (a Dutch equivalent of Library of Congress Subject Headings specifically designed for use in public libraries). However, sometimes adjustments are necessary to adapt keywords for PIM. This can be simple, like using a broader term as the PIM keyword when the work might ordinarily be assigned a much narrower term. For example, the Dutch thesaurus includes headings for individual soccer clubs, such as “Ajax Soccer Club” and “PSV Soccer Club.” Using these specific narrow terms would separate materials on the shelf, classing books on the Ajax soccer club under “Sport en Spel>Ajax” and books on PSV under “Sport en Spel>PSV.” Because keywords are filed alphabetically within categories, both of these books on soccer clubs would be separated by alphabetic distance, with “Ajax” under “A” and “PSV” with the “P”s. Instead, the broader term for “soccer clubs” (“Voetbalclubs”) is applied to ensure they file together. These changes are recorded and documented in the PIM literature maintained by NBD Biblion; however, the original subject headings are not changed in the Dutch NBD Biblion thesaurus. Rather, a “see” or “see also” reference might be included in the Dutch thesaurus to direct users to the term adjustments for PIM.

In an Online Public Access Catalog (OPAC) interface, what patrons see of the PIM classification depends heavily on the software used by the library. Some catalogs will only display the keyword; others are capable of displaying the colored pictograms as well. Libraries can license the rights to the pictograms in order to include them in OPAC development and display.


PIM is specifically designed for libraries with nonfiction collections of up to 15,000 items—any more than that and it becomes difficult to scale. For example, a smaller library may have about a dozen books about various types of ships, and all of these would be classed in PIM under that general category. However, a larger library may have many dozen—if not a hundred or more—books about ships, which would all be classed together using PIM. This presents the library user with a large number of books to browse with no secondary class (such as types of ships: sailboats, submarines, and so forth) used for division to aid the seeker. PIM is currently used in more than four hundred small-scale libraries in the Netherlands, mostly public libraries, but also schools, and it is especially popular in prison libraries.

Some public library systems include smaller branches that use PIM while the larger central branches still use SISO. These libraries and systems consider easy shelf browsing, exploration, and access a higher priority than consistent application of a classification system across multiple branches. This also reflects a focus on tailoring the library’s organization specifically to its local users, regardless of whether it is part of a branch system or if it stands alone.


NBD Biblion currently supplies pre-classified and labeled books and other materials to libraries as part of a larger cataloging and binding service in which a majority of Dutch libraries already participate. Now libraries can just choose to receive PIM labeling and processing rather than the traditional SISO classification. Libraries also have the option to purchase software and labels for printing from NBD Biblion in order to produce labels locally, in the event that labels need replacing, or if a library feels the need to make local adaptations. PIM classifications and keywords are included in the bibliographic records supplied to libraries, along with genre information, summaries (about 1,000 words, written by participating librarians and other professional authorities from all over the country), SISO classification, and Dutch NBD Biblion subject headings.

PIM is supported by the bibliographic description department at NBD Biblion, which consists of twelve full-time employees who create about 20,000 bibliographic records per year. Two developers within this department are directly responsible for PIM, but there are also many opportunities for users to offer input. In addition to the email address (pim@nbdbiblion.nl) used by librarians to submit suggestions, NBD Biblion also conducts panel discussions with librarians every other year to solicit feedback. One example of this was the major shift from twenty-six to  twenty-seven original pictograms: “religion” (“Religie”) was separated out from “spiritual life” (“Geestelijk leven”) due to popular demand, both from patrons who wanted the change for personal reasons as well as librarians who felt that the category was too large to encompass the number of materials at libraries with large religion sections. NBD Biblion seems very responsive to feedback from both librarians and patrons and is “constantly optimizing” the system.8 Any changes to PIM are processed retrospectively across previous cataloged titles and bibliographic descriptions to keep it current and adequately representative of user behavior and library collections.

Future Possibilities

Since its inception more than ten years ago, PIM continues to increase in popularity, and is in its sixth edition as of 2011. While currently only available in Dutch, NBD Biblion has received requests to translate PIM into other languages, especially Arabic and Turkish. Requests have also been made for NBD Biblion to develop a PIM-like system for larger library collections, and they are considering the possibility. However, scaling the system for larger collections entails significant challenges, the biggest of which entails developing additional levels of keywords, such as the previously described example about “ships.” Considering that until this year NBD Biblion has done little to no marketing for the classification system, PIM’s growth by word-of-mouth alone has been quite phenomenal.

So is this possible in the United States, a country 230 times the size of the Netherlands, with almost 800 times the number of libraries?9 Perhaps if we look at what characteristics make PIM successful, we can begin to evaluate the possibilities.

At the top of the list is PIM’s “audience-friendly” design: focusing on and aligning with observed patron needs and behaviors seems surely at the heart of its success. PIM offers an accessible and browseable physical collection while not significantly altering the search and retrieval experience
for those patrons who still prefer an online catalog search. Additionally, while offering consistency through centralized creation and distribution, it still offers libraries enough flexibility to make changes — local tweaks as well as contributing suggestions to larger, system-wide changes. Such participatory design in the initial design as well as ongoing maintenance of the scheme keeps it relevant to users and librarians, which surely helps contribute to lasting success.

NBD Biblion considered the scope of the project and targeted exactly which libraries and users PIM was designed to serve. By targeting smaller libraries and collections, with more niche needs and underserved by larger, all-encompassing classification schemes, NBD Biblion was able to keep the scope of the project and the scheme itself manageable, as opposed to an attempt to design a classification system meant to be used by all  libraries, everywhere. “One size fits all” often really fits none.

However, there is more to success than the design of the system. Without commitment on the part of NBD Biblion to devote time and resources to maintain PIM and keep it current, it would surely fall out of use as categories became outdated. Additionally, the centralized services provided
by NBD Biblion make it easy for libraries to use PIM—since most libraries already acquire 80 to 90 percent of their materials already cataloged, classified, bound, and labeled from NBD Biblion, they can simply choose which NBD Biblion-supported classification system should be applied to their purchases.

Scope would certainly play a major—if not the most important—role in undertaking such a project in the United States. The US may be a larger country with a larger number of libraries, but if the scope is chosen carefully, design and support of useful classification systems for smaller,
more niche groups is certainly possible.

Additionally, a secure commitment from a centralized organization to design, develop, maintain, and distribute the classification scheme would be required. Obvious choices include the Library of Congress or OCLC, although as the former struggles with funding issues and cutbacks such a
project may not be a feasible undertaking at this point in time. However, a vendor-based solution might also be viable, especially one that could offer simultaneous classification and acquisitions, as NBD Biblion does. Even a library branch or system might play this role, so long as the organization is stable and makes a solid commitment to the user-centered, participatory design of the system as well as ongoing, continued maintenance.

There are multitudes of classification systems in the world, besides just the ubiquitous Dewey and LC classifications. While these systems offer strength in longevity, it’s clear that more and more libraries in the US and abroad are interested in more user-based classification schemes while still maintaining centralized maintenance. PIM is an example from the Netherlands that we can look to as a success story to inspire similar progress all across the nation.


  1. NBD Biblion homepage, accessed Mar. 15, 2013.
  2. NBD Biblion is the product of the 2002 merger of two library service agencies, NBD and Biblion.
  3. Erwin Tuinstra and Linda de Man, personal interview with the author, Sept. 12, 2011.
  4. Ibid.
  5. NBD Biblion, PIM: Presentatiesysteem Informatieve Media, 6th ed. (Leidschendam, Netherlands: NBD Biblion, 2o11): 5.
  6. Ibid., 7.
  7. Ibid., 5.
  8. NBD Biblion homepage, accessed Mar. 15, 2013.
  9. American Library Association, “Number of Libraries in the United States,” accessed Mar. 15, 2013; Netherlands Institute for Social Research, “Table 1.1,” The Future of the Dutch Public Library, June 2008, accessed Mar. 15, 2013,