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The NIST Extensible Resource Data Model (NERDm): JSON schemas for rich description of data resources

Published by National Institute of Standards and Technology | National Institute of Standards and Technology | Catalog Last Checked: September 10, 2026 at 05:51 PM | Dataset Last Updated: September 02, 2017
The NIST Extensible Resource Data Model (NERDm) is a set of schemas for encoding in JSON format metadata that describe digital resources. The variety of digital resources it can describe includes not only digital data sets and collections, but also software, digital services, web sites and portals, and digital twins. It was created to serve as the internal metadata format used by the NIST Public Data Repository and Science Portal to drive rich presentations on the web and to enable discovery; however, it was also designed to enable programmatic access to resources and their metadata by external users. Interoperability was also a key design aim: the schemas are defined using the JSON Schema standard, metadata are encoded as JSON-LD, and their semantics are tied to community ontologies, with an emphasis on DCAT and the US federal Project Open Data (POD) models. Finally, extensibility is also central to its design: the schemas are composed of a central core schema and various extension schemas. New extensions to support richer metadata concepts can be added over time without breaking existing applications. Validation is central to NERDm's extensibility model. Consuming applications should be able to choose which metadata extensions they care to support and ignore terms and extensions they don't support. Furthermore, they should not fail when a NERDm document leverages extensions they don't recognize, even when on-the-fly validation is required. To support this flexibility, the NERDm framework allows documents to declare what extensions are being used and where. We have developed an optional extension to the standard JSON Schema validation (see ejsonschema below) to support flexible validation: while a standard JSON Schema validater can validate a NERDm document against the NERDm core schema, our extension will validate a NERDm document against any recognized extensions and ignore those that are not recognized. The NERDm data model is based around the concept of resource, semantically equivalent to a schema.org Resource, and as in schema.org, there can be different types of resources, such as data sets and software. A NERDm document indicates what types the resource qualifies as via the JSON-LD "@type" property. All NERDm Resources are described by metadata terms from the core NERDm schema; however, different resource types can be described by additional metadata properties (often drawing on particular NERDm extension schemas). A Resource contains Components of various types (including DCAT-defined Distributions) that are considered part of the Resource; specifically, these can include downloadable data files, hierachical data collecitons, links to web sites (like software repositories), software tools, or other NERDm Resources. Through the NERDm extension system, domain-specific metadata can be included at either the resource or component level. The direct semantic and syntactic connections to the DCAT, POD, and schema.org schemas is intended to ensure unambiguous conversion of NERDm documents into those schemas. As of this writing, the Core NERDm schema and its framework stands at version 0.7 and is compatible with the "draft-04" version of JSON Schema. Version 1.0 is projected to be released in 2025. In that release, the NERDm schemas will be updated to the "draft2020" version of JSON Schema. Other improvements will include stronger support for RDF and the Linked Data Platform through its support of JSON-LD.

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Complete Metadata
@type dcat:Dataset
accessLevel public
bureauCode 
[
  "006:55"
]
conformsTo http://json-schema.org/draft-04/schema
contactPoint 
{
  "fn": "Raymond Plante",
  "hasEmail": "mailto:raymond.plante@nist.gov"
}
description The NIST Extensible Resource Data Model (NERDm) is a set of schemas for encoding in JSON format metadata that describe digital resources. The variety of digital resources it can describe includes not only digital data sets and collections, but also software, digital services, web sites and portals, and digital twins. It was created to serve as the internal metadata format used by the NIST Public Data Repository and Science Portal to drive rich presentations on the web and to enable discovery; however, it was also designed to enable programmatic access to resources and their metadata by external users. Interoperability was also a key design aim: the schemas are defined using the JSON Schema standard, metadata are encoded as JSON-LD, and their semantics are tied to community ontologies, with an emphasis on DCAT and the US federal Project Open Data (POD) models. Finally, extensibility is also central to its design: the schemas are composed of a central core schema and various extension schemas. New extensions to support richer metadata concepts can be added over time without breaking existing applications. Validation is central to NERDm's extensibility model. Consuming applications should be able to choose which metadata extensions they care to support and ignore terms and extensions they don't support. Furthermore, they should not fail when a NERDm document leverages extensions they don't recognize, even when on-the-fly validation is required. To support this flexibility, the NERDm framework allows documents to declare what extensions are being used and where. We have developed an optional extension to the standard JSON Schema validation (see ejsonschema below) to support flexible validation: while a standard JSON Schema validater can validate a NERDm document against the NERDm core schema, our extension will validate a NERDm document against any recognized extensions and ignore those that are not recognized. The NERDm data model is based around the concept of resource, semantically equivalent to a schema.org Resource, and as in schema.org, there can be different types of resources, such as data sets and software. A NERDm document indicates what types the resource qualifies as via the JSON-LD "@type" property. All NERDm Resources are described by metadata terms from the core NERDm schema; however, different resource types can be described by additional metadata properties (often drawing on particular NERDm extension schemas). A Resource contains Components of various types (including DCAT-defined Distributions) that are considered part of the Resource; specifically, these can include downloadable data files, hierachical data collecitons, links to web sites (like software repositories), software tools, or other NERDm Resources. Through the NERDm extension system, domain-specific metadata can be included at either the resource or component level. The direct semantic and syntactic connections to the DCAT, POD, and schema.org schemas is intended to ensure unambiguous conversion of NERDm documents into those schemas. As of this writing, the Core NERDm schema and its framework stands at version 0.7 and is compatible with the "draft-04" version of JSON Schema. Version 1.0 is projected to be released in 2025. In that release, the NERDm schemas will be updated to the "draft2020" version of JSON Schema. Other improvements will include stronger support for RDF and the Linked Data Platform through its support of JSON-LD.
distribution 
[
  {
    "title": "ejsonschema: Software for Validating JSON supporting extension schemas",
    "format": "GitHub repository",
    "accessURL": "https://github.com/usnistgov/ejsonschema",
    "description": "This software repository provides Python software that extends the community software library, python-jsonschema (https://github.com/python-jsonschema/jsonschema) to support NERDm's extension framework.  Use the scripts/validate script to validate NERDm documents on the command line.  (Type "validate -h" for more information.)"
  },
  {
    "title": "NERDm Support Software",
    "format": "GitHub repository",
    "accessURL": "https://github.com/usnistgov/oar-metadata",
    "description": "This software repository includes a Python package, "nistoar.nerdm", that aids in creating and handling NERDm documents.  In particular, it includes converters that convert NERDm instances into other formats (like POD, schema.org, and DCAT).  It can also transform NERDm documents conforming to earlier versions of the schemas to that of the latest versions."
  },
  {
    "title": "README",
    "format": "text file",
    "accessURL": "https://github.com/usnistgov/oar-metadata/blob/integration/model/README-NERDm.md",
    "description": "A general overview of the NERDm schema design and files"
  },
  {
    "title": "The NERDm JSON Schema Files",
    "format": "GitHub folder",
    "accessURL": "https://github.com/usnistgov/oar-metadata/tree/integration/model",
    "description": "This directory contains the latest (and previous) versions of the core NERDm Schema and various extensions.  All files with names of the form, "*-schema*.json" are JSON Schema definition files; those that do not include a version in the file name represent the latest versions.  The latest version of the core schema is called "nerdm-schema.json", and schemas with names of the form, "nerdm-[ext]-schema.json", contain extension schemas.  All NERDm schemas here are documented internally, including semantic definitions of all terms."
  },
  {
    "title": "Example NERDm Documents",
    "format": "GitHub folder",
    "accessURL": "https://github.com/usnistgov/oar-metadata/tree/integration/model/examples",
    "description": "This folder contains example NERDm documents that illustrate the NERDm data model and use of extension schemas.  These all can be validated using the ejsonschema validate script."
  }
]
identifier 5BD6C3C9109D1355E0531A570681CCEF1870
issued 2025-02-13
keyword 
[
  "FAIR",
  "JSON-LD",
  "data management",
  "data repositories",
  "metadata",
  "schema"
]
landingPage https://data.nist.gov/od/id/5BD6C3C9109D1355E0531A570681CCEF1870
language 
[
  "en"
]
license https://www.nist.gov/open/license
modified 2017-09-02 00:00:00
programCode 
[
  "006:045"
]
publisher 
{
  "name": "National Institute of Standards and Technology",
  "@type": "org:Organization"
}
references 
[
  "https://doi.org/10.1007/978-3-540-24750-0_3",
  "https://doi.org/10.1145/507533.507536",
  "https://json-schema.org/",
  "https://resources.data.gov/resources/dcat-us/",
  "https://www.w3.org/TR/vocab-dcat-2/"
]
theme 
[
  "Information Technology:Data and informatics"
]
title The NIST Extensible Resource Data Model (NERDm): JSON schemas for rich description of data resources

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