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Unified Medical Language System® (UMLS®)

RxNorm Source Inclusion Evaluation Criteria and Background Questions

Version 1.1 - September 21, 2018

To consider a new source vocabulary for inclusion in RxNorm, the National Library of Medicine (NLM) needs to understand details about your vocabulary and why you would like NLM to add your vocabulary to RxNorm. Answering the questions below will provide NLM with a better understanding of your vocabulary and if it meets the criteria for inclusion. Please provide as much information as possible to assist NLM in making an informed decision regarding the inclusion of your vocabulary in RxNorm. NLM reserves the right to change these questions and criteria at any time.

You can download an editable version of the questions below and then submit the completed document to

Inclusion Evaluation Criteria

Value to RxNorm

NLM wants to understand the use cases for your vocabulary and its user communities.

  • What are the use cases for your vocabulary?
    • Which user communities will the vocabulary serve?
  • How will adding your vocabulary to RxNorm contribute to interoperability among drug resources?
    • For example, will the addition of your vocabulary help link currently available electronic resources, such as patient records or data elements?
  • Do you include national drug code (NDC) data?
    • How is your NDC data maintained?
  • In addition to RxNorm, NLM maintains the Unified Medical Language System (UMLS). The UMLS is a large biomedical thesaurus with nearly 200 different vocabularies and is updated twice a year. All vocabularies included in RxNorm are also included in the UMLS.
    • Considering the content of your vocabulary and its update frequency, would your vocabulary be a better fit in the UMLS?
    • Why should your vocabulary be included in RxNorm instead of directly in the UMLS?

Source Vocabulary Content

NLM wants to understand your vocabulary content, including the organizational principles and editorial guidelines used to create your vocabulary.

  • Are thesaurus characteristics and principles used to create your vocabulary?
    • Is it concept-oriented (i.e., organized by meaning)?
    • Are there preferred terms or synonyms?
    • Do you have codes/identifiers associated with names?
    • Is there a principled hierarchy?
    • Do explicitly defined relationships exist between the terms, such as broader than/narrower than relationships?
    • Are there definitions or other associated information?
    • Are there mappings or connections to other vocabularies?
  • Do you use standard naming conventions for drug information terms (e.g. United States Adopted Names (USAN), International nonproprietary names (INN), the Unified Code for Units of Measure (UCUM))?
    • What standard conventions do you use?
  • Are the meanings of your terms clearly distinct when seen alone, rather than in the associated context? For example, the term “calcium” seen alone can refer to the element or a drug class.
    • Will there be many cases where the ‘face’ meaning of a term is different from the meaning of the same term in other areas of biomedicine?
  • What parts of your vocabulary would NLM be permitted to publish in RxNorm?
    • For example, will the drug name and NDC be published in RxNorm?
  • Are your generic, trade, and branded products fully differentiated with respect to identifiers and NDCs?
  • Do you maintain current information about whether drugs are off-the-market?
    • How is off-the-market data represented and with what metadata?

Technical Process and Development

NLM wants to understand the technical aspects of your vocabulary.

  • Is the vocabulary available in a well-structured, computable electronic format?
    (NLM cannot accept printed publications, nor convert them.)
    • What is the format?
    • What is the data size of your vocabulary?
    • How many terms are in your vocabulary?
    • Is a sample set of files and documentation available?
    • Is there a technical contact person for questions about the files?
  • Will you provide your vocabulary data files to NLM free of charge?
    • If yes, how will you provide your data files to NLM?
    • Will there be an automated download capability?
  • Do you provide fully specified drug names with ingredient, strength, and dose form in one data field or must the fully specified names be built across fields/tables?
    • For example, RxNorm currently concatenates ingredient, strength and dose form information to create a final drug name for some vocabularies. Will your vocabulary require this type of data processing?

Background Questions

NLM wants to understand additional details about your vocabulary.

  • Is your vocabulary actively maintained?
    (RxNorm will only accept vocabularies that are actively maintained.)
    • What type of ongoing support does your vocabulary receive to ensure that it will remain a viable asset to RxNorm?
    • Is your vocabulary and its updates officially sponsored?
    • If so, please describe by whom and how your vocabulary is sponsored?
    • Who is the responsible party or parties for your vocabulary?
  • How often do you update your vocabulary content?
    • What is your update model?
  • Who is the vocabulary author?
    (Some vocabularies are authored and maintained by different organizations.)
    • Who creates your vocabulary content?
    • Who owns the vocabulary content?
  • Do you have a mechanism to maintain the integrity of your vocabulary?
    • How do you maintain the integrity of your vocabulary?
  • Is there a point of contact if there are content related questions?
    • Do they have computer connectivity, equipment, and support?
  • Do you have an online browsing resource that NLM editors can use to access your vocabulary data or additional data about the drug information in your vocabulary?

Terms of Agreement

Source vocabularies included in RxNorm follow the terms of the UMLS Metathesaurus License Agreement. Please examine the UMLS Metathesaurus License Agreement and resolve any questions about copyright ownership.

  • According to Appendix 1 and section 12 of the UMLS Metathesaurus License Agreement (and outlined on the License Category Help page), what have you determined your license restriction level to be (0, 1, 2, 3, or 4)?
  • Would you allow a subset of your vocabulary data to be published in RxNorm and the UMLS at a lower restriction level?
  • Would you allow your vocabulary to be exposed to users through open web interfaces and tools and/or open downloads and application programming interfaces (APls) without user authentication?

Last Reviewed: September 21, 2018