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A structure (usually hierarchical) in which a body of information or knowledge is categorized, allowing an understanding of how that body of knowledge can be broken down into parts and how its various parts relate to each other


Taxonomies are used to organize information or knowledge in systems, thereby helping users to find it. They represent a predefined organizational structure that can cover a range of subjects from general industries or fields of study to the relevant words and terms unique to the business. They are usually arranged hierarchically, reflect general to more specific relationships and show correlations between subject areas.

The word comes from the Greek τάξις, taxis (meaning "order", "arrangement") and νόμος, nomos ("law" or "science"). Taxonomies, or taxonomic schemes, are composed of taxonomic units known as taxa (singular taxon), or kinds of things that are arranged frequently in a hierarchical structure. Typically they are related by subtype-supertype relationships, also called parent-child relationships. In such a subtype-supertype relationship the subtype element has by definition the same constraints as the supertype element plus one or more additional constraints. Major taxonomy development tasks are: taxonomy scoping, taxonomy building and taxonomy evaluation.

Taxonomies are part of the intellectual infrastructure: roads, transportation systems, but not cars, or types of cars! Taxonomies are part of creating smart organizations: self awareness, capable of learning and evolving.

Developing a taxonomy

Stage 1. Determine taxonomy requirements

Necessary considerations:

  • What is the problem the user is trying to solve?
  • What content needs to be organized?
  • How will the taxonomy be used?
  • What is the scope and purpose of the taxonomy?

Stage 2. Identify concepts

Possible tasks:

  • Determine the sponsor and the stakeholders.
  • Assign a team leader. Recruit team members if necessary.
  • Determine the target audience.
  • Determine the users’ information needs. Interview users about their information needs/uses/problems.
  • Define scope and purpose of the taxonomy.
  • Determine objectives to be accomplished.
  • Determine if funding (budget) is available for the taxonomy.
  • Find out what technology the user plans on using (if any) and what constraints the technology might have on the taxonomy.
  • Develop a communication plan to keep stakeholders informed.
  • Create the schedule.

Necessary considerations:

Part A- Discover where and what the content is
  • What content will the taxonomy be used to organize?
  • Where is the existing content located?
  • How is the content structured?
  • Who is responsible for the content?
  • What is the value of the content?
Part B. Perform a content inventory
  • What subjects/topics are covered by the content?
  • What format is the content in?
  • What types of content are there?
  • What are the metadata (if any) for the content?
Part C. Conduct user interviews
  • What concepts and information do users search/browse for most often?
  • How do users search for information?

Possible outputs:

  • Business case document.
  • Scope statement.
  • Description of the expectations for the project.
  • Project plan with tasks and schedule.
  • Description of the technology that will be used.
  • Buy-in from sponsors and stakeholders.
  • List of interview questions.
  • Transcript of the interviews.
  • Summary of the users’ information needs.

Stage 3. Develop draft taxonomy

Possible tasks:

  • Establish guidelines and standards for format of terms and construction of relationships.
  • Examine existing controlled vocabularies to determine if they could be used as is or modified to meet the user’s needs.
  • Develop upper levels of the taxonomy structure.
  • Use candidate terms and other resources to build depth into the taxonomy.(Other resources can include existing thesauri, dictionaries, handbooks, file directory structures, web site categories, etc.)
  • Reconcile language and terminology issues.
  • Develop hierarchical relationships between terms.
  • Develop cross-references between synonyms.
  • Develop scope notes to define the terms.
  • Build enough depth into the taxonomy so that the overall structure can be validated.

Possible outputs:

  • A draft taxonomy ready for review.
  • Guidelines and standards for constructing terms and relationships. (Example: ANSI Z39.19, local guidelines)

Stage 4. Review with users and SMEs

Possible tasks:

  • Ask the users and subject matter experts to examine the draft taxonomy and suggest changes.
  • Discuss and determine appropriateness of requested changes.
  • Perform usability studies of the taxonomy.

Necessary considerations:

  • Does the structure make sense to the users?
  • Are the major concepts included in the taxonomy?
  • Does the taxonomy go too deep in any place?
  • Are the users and subject matter experts able to validate the taxonomy?

Possible outputs:

  • List of user comments and suggested changes.
  • Record of suggested changes to the taxonomy, including any decisions about and reasons for changes to the overall taxonomy design.
  • Results of the usability studies.

Stage 5. Refine taxonomy

Possible tasks:

  • Review user and subject matter expert feedback.
  • Incorporate agreed-to changes.
  • Incorporate changes based on analysis of results of the usability study.
  • Continue to build depth into the taxonomy. How deep the taxonomy should be is dependent on user feedback and whether the taxonomy nodes retrieve any content.
  • Solicit input from users and subject matter experts during this process.
  • Document all changes and decisions regarding the taxonomy.
  • Establish evaluation and testing criteria for the taxonomy.

Possible outputs:

  • Refined taxonomy.
  • Evaluation and testing criteria for the taxonomy.

Stage 6. Apply taxonomy to content


  • Taxonomy implemented in users’ environment to organize content and/or navigate through and to content.

Possible outputs:

  • Summary of implementation advice provided to user.
  • Guidelines for using the taxonomy to tag content.
  • Taxonomy is implemented and utilized by the users.

Stage 7. Manage and maintain taxonomy

Necessary considerations:

  • Are the users satisfied with the taxonomy?
  • Is the taxonomy current?
  • How is the taxonomy governed?
  • How will the taxonomy be maintained?
  • Who will maintain the taxonomy?
  • How are changes implemented?


The taxonomy of the Fast Reactor Knowledge Preservation System

FIG. 1. Structure of the two top levels of the FRKPS

The taxonomy of the Fast Reactor Knowledge Preservation System - FRKPS consists of two upper levels which are represented as a two-dimensional matrix. The elements of the upper row are stages of implementation of reactor technology (1st structural level of FRKPS), and the columns under the upper row elements include topical sections corresponding to given stages of reactor technology implementation (2nd structural level of FRKPS). This matrix is shown in Fig. 1. It is proposed to divide each topical section presented in the matrix into progressively detailed subsections and connect them in such a way that each subsequent level is a more detailed presentation of the previous level. Therefore, each topical section of the upper level will have a certain branched root structure consisting of specialized topical sections.

The matrix is claimed to be versatile because its structure was developed with a hypothetical, generalized SFR power plant in mind. Moreover, this structure is applicable not only to any SFR nuclear power plant irrespective of the stage of its development, but also to any experimental fast reactor. This structure would undoubtedly be redundant with reference to some specific reactor facilities. However, this redundancy has an advantage because a given document may have information on any one of several aspects of the SFR. It should be noted that the matrix structure development is still far from complete. First, topical sections of the upper level require more development and expansion. Second, the root structure should be developed for all these sections. However, this approach to the development of FRKPS taxonomy with separation of stages and topical sections of reactor technology as shown in the matrix is considered to be highly useful.

Taxonomy with multiple dimensions

FIG. 2. An example of taxonomy with multiple dimensions
In most cases, the same knowledge may be used by different persons in different contextual backgrounds. Thus, the knowledge could be related to several categories. This brings a challenge to the taxonomy. It might be impossible to put all the knowledge into categories perfectly if these categories are established in terms of only one dimension. Taxonomy with multiple dimensions is essential in all types of nuclear organizations on account of their complicated business fields. The dimensions could be projects, types, disciplines, facilities, equipments, sources and locations, etc. This will facilitate users to filter or search knowledge according to their own purposes or dimensions. The taxonomy can be built in the form of a tree structure which is shown as Fig. 2.

Related articles


Information architecture

Semantic net

External Links

  1. Information Architecture on Wikipedia
  2. Taxonomy on Wikipedia