The NIST Extensible Resource Data Model:
a Reader's Guide to NERDm Metadata

Table of Contents

Introduction

The NERDm schema is used to encode metadata describing various kinds of resources--datasets, data collections, web portals, software, and tools--that are offered by NIST through its data science portal. Resources are the main kind of "thing" that NERDm metadata is used to describe, and there are different types resources. NERDm metadata is encoded in JSON format (specifically, JSON-LD), but this guide attempts to describe the metadata without relying on much knowledge of that format. The purpose of this document is to guide readers that wish to inspect NERDm JSON records and understand that the metadata means.

(Software developers that wish to read and process NERDm records may also find this document useful for browsing metadata definitions. However, they can also consult the JSON Schema definition documents useful. The NERDm schema has two parts: a core schema, and an an extension schema for describing data publications.)

What a NERDm record looks like

A NERDm record looks like JSON, because it is JSON(!). Below is an annotated example of NERDm metadata describing a hypothetical data resource. The metadata is in the form of a set of properties. A property is a piece of metadata that has a name and a value. The value can be a single value (e.g. text, a number, true/false), a list of values, or a complex values made up of sub-properties. 

            {
                "@id": "ark:/88434/pdr01893t",
                "@type": [ "nrdp:DataPublication", "nrdp:PublicDataResource" ],
                "title": "Moby Dick: an analysis",
                "description": [
                   "Moby-Dick is about a man and a whale",
                   "It does not end well."
                ],
                "contactPoint": {
                    "hasEmail": "mailto:Herman.Melville@pequod.com",
                    "fn": "Herman Melville",
                    "address": [
                        "Arrowhead",
                        "Pittsfield, Mass."
                    ]
                }
            }
1. property names
2. simple text value
3. property value that is a list of text values
4. property value that is a set of "sub-properties"
Annotation notes for above example:
  1. property names -- These show the name of each property; the name appears before a colon (:). The links in this example (which are not part of the JSON format) link to the definition of the property in the reference section below.
  2. simple text value -- The title has a simple text value (also called a string). Other simple values can be numbers or the words, true, false, or null. Only text values are surrounded by quotes.
  3. property value that is a list of text values -- The value for the description is a list of text values. A list value is surrounded by square brackets ([...]).
  4. property value that is a set of "sub-properties" -- Some properties can be more complex, requiring multiple pieces of intformation, each with its own "sub-property" name. The sub-properties are kept together by surrounding them with curly brackets ({...}).

Note also that spaces (outside of quoted text) are optional in the JSON syntax. Thus, you may encounter JSON without the extra spaces that make it easier to read.

What kinds of information are in a NERDm record

A NERDm record describes, in general, a data resource--that is, a source of data that can be used in research. There are different kinds of resources, such as data files, databases, software, and even data web portals that include on-line tools. All data resources are described with a common set of metadata properties; these properties are defined as part of the generic Resource type. Some types of resources can have additional, specialized metadata. For example, the DataPublication Resource type defines the authors property that lists the authors presenting the data.

A data resource often made up of one or more data files that can be downloaded. If the resource is a database, it may instead provide a search page available through a web browser or an API to access the data through a program. These various ways to access the data are represented as resource components. Similar to the Resource type, a there is a common set of metadata for describing components; these are captured as part of the generic Component type. The most common type of component is the DataFile type, representing a downloadable data file; one of its special properties is the downloadURL, indicating the URL to use to download the file. 

            {
                "@id": "ark:/88434/pdr01893t",
                "@type": [ "nrdp:DataPublication", "nrdp:PublicDataResource" ],
                "title": "Moby Dick: an analysis",
                "doi": "doi:10.18434/T488S8",
                "description": [
                   "Moby-Dick is about a man and a whale",
                   "It does not end well.",
                   "We analyze the text for its appropriateness as a training set for AI-driven obsession."
                ],
                "contactPoint": { ... },
                "components": [
                    {
                        "@id": "cmps/aggregates/wordfreq.csv",
                        "@type": [ "nrdp:DataFile", "dcat:Distribution" ],
                        "filepath": "cmps/aggregates/wordfreq.csv",
                        "downloadURL": "https://data.nist.gov/od/id/pdr01893t/aggregates/wordfreq.csv",
                        "title": "Word Frequency Data",
                        "size": "209531"
                    },
                    {
                        "@id": "cmps/aggregates",
                        "@type": [ "nrdp:Subcollection" ],
                        "filepath": "cmps/aggregates",
                        "title": "Aggregate data"
                        "description": "This collection contains the computed aggregate data." 
                    }
                ]
            }
1. NIST-internal persistent identifier
2. Resource types
3. Externally citable identifier
4. Metadata description of the resource as a whole.
5. Metadata description of each component (file, subcollection, etc.) of the resource.
Annotation notes for above example:
  1. NIST-internal presistent identifier -- Every resource available through the NIST Science Data Portal has its own unique identifier which starts with ark:/88434/.
  2. Resource types -- the @type property indicates the type of resource this is. This example is both a PublicDataResource and a DataPublication.
  3. Externally citable identifier -- a DOI is an optional secondary identifier that can be assigned to a resource (although not all resources have one). When one exists, this identifier can be used to cite the data in other publications.
  4. Metadata description of the resource as a whole -- these metadata (and others not shown) describe the resource as a whole.
  5. Metadata description of each component of the resource -- the components property contains a list of component descriptions. Each set of subproperties describes a different data file, subcollection, or other type of component.

NERDm Reference: Named Types

Index

Resource Types

Named Type
Resource

JSON type:
object
What it represents:
a resource (e.g. data collection, service, website or tool) that can participate in a data-driven application.

There are different types of Resources; this Named Type represents a generic resource. The other Resource types described later in this section add additional metadata to the base set shown here to describe more specific kinds of resources (like data publications, APIs, etc.)
Where it is used:
as the basis for extension type, PublicDataResource

Properties:

Property of the Resource type
title
What it represents:
Human-readable, descriptive name of the resource
Value type:
text
Example Values:
"The NIST High Temperature Superconducting Materials Database",
"Organic Contaminants in Non-Fortified Human Milk"
Property of the Resource type
version
What it represents:
a string indicating the version of the release of this resource
Value type:
text
Example Values:
"1.0.5",
"11"
Property of the Resource type
versionHistory
What it represents:
a list describing the release of different versions of this resource
Value type:
list of VersionRelease objects
Property of the Resource type
replaces
What it represents:
a listing of other existing resources that are deprecated by this resource
Value type:
list of references to other resources
Property of the Resource type
isReplacedBy
What it represents:
another existing resource that should be considered a replacement for this resource
Value type:
a reference to another resource
Property of the Resource type
description
What it represents:
Human-readable description (e.g., an abstract) of the resource
Value type:
list of text values
Notes:
  • Each list element should be considered as a separate paragraph.
Property of the Resource type
keyword
What it represents:
Tags (or keywords) help users discover your dataset; please include terms that would be used by technical and non-technical users.
Value type:
list of text values
Notes:
  • Each value in the list represents a different keyword. Keywords can be made up of multiple words
Example Values:
metals,
quantum mechanics
Property of the Resource type
topic
What it represents:
A tag or label taken from a pre-defined vocabulary for a thing or concept that this resource addresses or speaks to
Value type:
list of Topic objects
Property of the Resource type
modified
What it represents:
Most recent date on which the dataset was changed, updated or modified.
Value type:
ISO8601DateRange object
Notes:
  • The value is usually a single formated date, like 2017-04-21, or a data and time, like 2019-02-23T14:31:10.3
  • A special format is used to indicate the resource is regularly update; e.g., R/P1W (for once a week); see ISO8601DateRange for details.
Property of the Resource type
issued
What it represents:
Date of formal issuance of the resource
Value type:
FlexibleDate object
Notes:
  • The value is usually a single formated date, like 2017-04-21
Property of the Resource type
publisher
What it represents:
The publishing entity and optionally their parent organization(s).
Value type:
Organization object
Property of the Resource type
contactPoint
What it represents:
Contact information for getting more information about this resource
Value type:
ContactInfo object
Property of the Resource type
accessLevel
What it represents:
The degree to which this dataset could be made publicly-available, regardless of whether it has been made available
Value type:
text
Allowed Values:
public
Data asset is or could be made publicly available to all without restrictions
restricted public
Data asset is available under certain use restrictions
non-public
Data asset is not available to members of the public
Property of the Resource type
license
What it represents:
A pointer to the primary license or non-license (i.e. Public Domain) statement with which the dataset or API has been published
Value type:
text (URL)
Property of the Resource type
rights
What it represents:
information regarding access or restrictions based on privacy, security, or other policies
Value type:
text
Property of the Resource type
components
What it represents:
a listing of the various component resources, tools, and distributions of this resource. A component usually represents data that is part of this resource that be retrieved or a way to interact with the data.
Value type:
list of Component objects
Notes:
  • This list often includes the list of data files (represented as DataFile components) that are available to download.
  • Data files can be organized into a hierarchy of subcollections (like file folders). When this is the case, this list will also include Subcollection components. Both DataFile and Subcollection components included a filepath that indicates where it is located in the hierarchy.
Property of the Resource type
conformsTo
What it represents:
URI used to identify a standardized specification the resource conforms to
Value type:
text (URL)
Notes:
  • This identifier might refer to a file or dataset format, to database schema, or to a web API.
Property of the Resource type
isPartOf
What it represents:
The collection of which the dataset is a subset
Value type:
ResourceReference object
Notes:
  • The resource being referenced normally is one that is also described by a NERDm record which is accessible via its identifier (given in the proxyFor property).
Property of the Resource type
language
What it represents:
The primary language used in the dataset
Value type:
list of text values
Property of the Resource type
landingPage
What it represents:
a URL to a human-friendly web page that represents the home or gateway to the resources that are part of this dataset. This page represents the definitive location for accessing the resource.
Value type:
text (URL)
Property of the Resource type
references
What it represents:
Related documents such as literature articles, technical reports about a dataset, developer documentation, etc. that refer to or describe this resource
Value type:
list of BibliographicReference objects
Property of the Resource type
theme
What it represents:
Main thematic category of the dataset.
Value type:
list of text values
Notes:
  • Values are taken from the Taxonomy of NIST Research Areas.
Property of the Resource type
@id
What it represents:
The NIST-assigned unique identifier for the resource
Value type:
text
Notes:
  • This identifier takes a the form of a NIST-issued ARK identifier (and thus starts with ark:/88434/)
  • If the resource has been assigned a DOI, it will appear in the doi
Property of the Resource type
doi
What it represents:
A Digital Object Identifier (DOI) in non-resolving form.
Value type:
text
Example Values:
"doi:10.18434/T42S31"
Property of the Resource type
ediid
What it represents:
the NIST EDI identifier assigned to the resource. This is the identifier assigned by the MIDAS system.
Value type:
text
Property of the Resource type
abbrev
What it represents:
An abbreviated form of the resource's title. This abbreviation can be used as a compact, human-readable reference to the resource.
Value type:
list of text values
Example Values:
"SRD 13",
"JRes-NIST"
Property of the Resource type
@type
What it represents:
The linked-data class types for this resource. The labels given in this list indicate the kind of thing is being described by metadata.
Value type:
list of text values
Notes:
  • This property is a list because it is possible for a resource to be catorgorized as multiple types simultaneously
  • The first value in the list will be the most specific resource type that applies to the resource and should be considered, therefore, its primary type.
  • Often, the values refer to Named Types defined explicitly in the NERDm schema (e.g. DataPublication); in this case, the resource metadata can include the extended metadata properties for that type.
  • Some values are just semantic labels that do not imply the existance of additional extended metadata.
  • These values are intended to be compliant with use of @type property in the JSON-LD format.
Example Values:
"nrdp:DataPublication",
"nrdp:SRD",
"dcat:Dataset"

Named Type
PublicDataResource

JSON type:
object
What it represents:
a resource that can/should have a record in NIST's public data listing (PDL)
Where it is used:
as the basis for extension type, DataPublication

Properties:

Inherited from Resource:
title, version, versionHistory, replaces, isReplacedBy, description, keyword, topic, modified, issued, publisher, contactPoint, accessLevel, license, rights, components, conformsTo, isPartOf, language, landingPage, references, theme, @id, doi, ediid, abbrev, @type
Property of the PublicDataResource type
accrualPeriodicity
What it represents:
Frequency with which dataset is published.
Value type:
fixed value: "irregular" or text
Property of the PublicDataResource type
bureauCode
What it represents:
an identifier provided by the OMB Circular A-11, Appendix C that identifies the originating federal agency
Value type:
list of text values
Property of the PublicDataResource type
programCode
What it represents:
an identifier provided by the Federal Program Inventory that identifies the primary program related to this data asset
Value type:
list of text values
Property of the PublicDataResource type
dataQuality
What it represents:
Whether the dataset meets the agency's Information Quality Guidelines
Value type:
boolean
Property of the PublicDataResource type
primaryITInvestmentUII
What it represents:
The IT Unique Investment Identifier (UII) that is associated with this dataset
Value type:
text
Property of the PublicDataResource type
systemOfRecords
What it represents:
The URL to the System of Records Notice related to this dataset if is so designated under the Privacy Act of 1974
Value type:
text

Named Type
DataPublication

JSON type:
object
What it represents:
Data presented by one or more authors as citable publication
Where it is used:

Properties:

Inherited from Resource:
title, version, versionHistory, replaces, isReplacedBy, description, keyword, topic, modified, issued, publisher, contactPoint, accessLevel, license, rights, components, conformsTo, isPartOf, language, landingPage, references, theme, @id, doi, ediid, abbrev, @type
Inherited from PublicDataResource:
accrualPeriodicity, bureauCode, programCode, dataQuality, primaryITInvestmentUII, systemOfRecords
Property of the DataPublication type
subtitle
What it represents:
a secondary or sub-title for the resource
Value type:
list of text values
Property of the DataPublication type
aka
What it represents:
other (unofficial) titles that this resource is sometimes known as
Value type:
list of text values
Property of the DataPublication type
authors
What it represents:
the ordered list of authors of this data publication
Value type:
list of Person objects
Property of the DataPublication type
recommendedCitation
What it represents:
a recommended formatting of a citation to this data publication
Value type:
text

Component Types

Named Type
Component

JSON type:
object
What it represents:
A description of one component of a resource. A component can be a downloadable file, a subcollection of files, an API, or search page.

This Named Type represents a generic component; other Component types described later in this section represent specific kinds of components.
Where it is used:
as a value type for the components list property of the Resource type
as the basis for extension type, IncludedResource
as the basis for extension type, DownloadableFile
as the basis for extension type, Subcollection
as the basis for extension type, AccessPage
as the basis for extension type, API

Properties:

Property of the Component type
@id
What it represents:
a relative identifier for the distribution It can be appended to its resource identifier to get a globally unique version of the identifier.
Value type:
text
Property of the Component type
@type
What it represents:
the types of components that this component can be classified as
Value type:
list of text values
Notes:
  • This property is a list because it is possible for a component to be catorgorized as multiple types simultaneously
  • An included value of nrd:Hidden indicates that the component is part of the NIST-internal management of the resource and is not expected to be useful to external users
  • These values are intended to be compliant with use of @type property in the JSON-LD format.
Example Values:
"nrdp:DataFile",
"nrdp:Subcollection",
"nrd:Hidden",
"dcat:Distribution"
Property of the Component type
title
What it represents:
a descriptive title for the component
Value type:
text
Property of the Component type
description
What it represents:
a description of the nature and contents of the component, including the role it plays as part of the resource
Value type:
text
Property of the Component type
topic
What it represents:
A tag or label taken from a pre-defined vocabulary for a thing or concept that this component addresses or speaks to
Value type:
list of Topic objects
Property of the Component type
conformsTo
What it represents:
URI used to identify a standardized specification the component conforms to
Value type:
text (URL)

Named Type
IncludedResource

JSON type:
object
What it represents:
A reference to another resource (which has its own record) that is a part of this resource
Where it is used:
as an allowed value type in the components property in the Resource type
as an allowed value type in the isPartOf property in the Resource type

Properties:

Inherited from Component:
@id, @type, title, description, topic, conformsTo
Inherited from ResourceReference:
@id, @type, title, proxyFor, resourceType
Property of the IncludedResource type
@id
What it represents:
a relative identifier for this component
Value type:
(see JSON schema)
Property of the IncludedResource type
resourceType
What it represents:
the linked-data class types for the included resource
Value type:
list of text values

Named Type
DownloadableFile

JSON type:
object
What it represents:
a description of a downloadable, finite stream of data
Where it is used:
as an allowed value type in the components property in the Resource type
as the basis for extension type, DataFile
as the basis for extension type, ChecksumFile

Properties:

Inherited from Component:
@id, @type, title, description, topic, conformsTo
Property of the DownloadableFile type
filepath
What it represents:
a name for the data file reflecting its hierarchical location in the data source collection
Value type:
text
Property of the DownloadableFile type
downloadURL
What it represents:
URL providing direct access to a downloadable file of a dataset
Value type:
text (URL)
Property of the DownloadableFile type
mediaType
What it represents:
The machine-readable file format (IANA Media Type or MIME Type) of the file’s downloadURL
Value type:
text
Property of the DownloadableFile type
format
What it represents:
A human-readable description of the file format of a distribution
Value type:
Format object
Property of the DownloadableFile type
checksum
What it represents:
a checksum for the file
Value type:
Checksum object
Property of the DownloadableFile type
size
What it represents:
the size of the file in bytes
Value type:
integer

Named Type
DataFile

JSON type:
object
What it represents:
a description of a downloadable file that was provided by the authors (as opposed to a system or checksum file produced by the publication system).
Where it is used:
as an allowed value type in the components property in the Resource type

Properties:

Inherited from Component:
@id, @type, title, description, topic, conformsTo
Inherited from DownloadableFile:
filepath, downloadURL, mediaType, format, checksum, size
Property of the DataFile type
describedBy
What it represents:
URL to the data dictionary for the distribution found at the downloadURL
Value type:
text (URL)
Property of the DataFile type
describedByType
What it represents:
The machine-readable file format (IANA Media Type or MIME Type) of the file’s describedBy URL
Value type:
text

Named Type
ChecksumFile

JSON type:
object
What it represents:
a downloadable file that contains the checksum value for a DataFile.
Where it is used:
as an allowed value type in the components property in the Resource type

Properties:

Inherited from Component:
@id, @type, title, description, topic, conformsTo
Inherited from DownloadableFile:
filepath, downloadURL, mediaType, format, checksum, size
Property of the ChecksumFile type
algorithm
What it represents:
the algorithm used to produce the checksum hash
Value type:
Topic object
Property of the ChecksumFile type
valid
What it represents:
A flag, if True, indicating the the hash value contained in this ChecksumFile is confirmed to be correct for its associated data file.
Value type:
boolean
Property of the ChecksumFile type
describes
What it represents:
Value type:
text (uri-reference)

Named Type
Subcollection

JSON type:
object
What it represents:
A grouping of components within a named subcollection of the resource
Where it is used:
as an allowed value type in the components property in the Resource type

Properties:

Inherited from Component:
@id, @type, title, description, topic, conformsTo
Property of the Subcollection type
filepath
What it represents:
a name for the data file reflecting its hierarchical location in the data source collection
Value type:
text
Property of the Subcollection type
contains
What it represents:
a listing of resource components that are directly part of this subcollection
Value type:
list of text values
Property of the Subcollection type
hasParent
What it represents:
The identifier for the parent collection that contains this subcollection
Value type:
text

Named Type
AccessPage

JSON type:
object
What it represents:
a web page that provides indirect access to the resource
Where it is used:
as an allowed value type in the components property in the Resource type
as the basis for extension type, SearchPage

Properties:

Inherited from Component:
@id, @type, title, description, topic, conformsTo
Property of the AccessPage type
accessURL
What it represents:
the URL for accessing this indirect access to the resource
Value type:
text (URL)
Property of the AccessPage type
format
What it represents:
A human-readable description of the file format of a distribution
Value type:
Format object

Named Type
SearchPage

JSON type:
object
What it represents:
a web page that can be used to search the contents of the resource
Where it is used:
as an allowed value type in the components property in the Resource type

Properties:

Inherited from Component:
@id, @type, title, description, topic, conformsTo
Inherited from AccessPage:
accessURL, format

Named Type
API

JSON type:
object
What it represents:
an application programming interface to the resource
Where it is used:
as an allowed value type in the components property in the Resource type

Properties:

Inherited from Component:
@id, @type, title, description, topic, conformsTo
Property of the API type
accessURL
What it represents:
the base URL for accessing the API.

This URL may or may not be resolvable (consult the documentation at the describedBy URL). With some APIs, this base URL will return information for accessing the full capabilities of the service.
Value type:
text (URL)
Property of the API type
describedBy
What it represents:
URL to a formal description or informal documentation of the API.
Value type:
text (URL)
Notes:
  • Use describedByType to help distinguish between formal and informal (i.e. human readable) descriptions: no describedByType value should indicate a human-readable document.
Property of the API type
describedByType
What it represents:
The machine-readable file format (IANA Media Type or MIME Type) of the API's describedBy URL.
Value type:
text
Notes:
  • If no value is given for this property, it can be assumed that the document given by the describedBy URL is human-readable documentation for the API.

Other Types

Named Type
FlexibleDate

JSON type:
object
What it represents:
a flexible format for a resource-related date
Where it is used:
as a value type for the issued property in the Resource type
as a value type for the issued property in the RelatedResource type

Named Type
RelatedResource

JSON type:
object
What it represents:
a descriptive reference to another resource that related to this one
Where it is used:
as a part of the value type for the isReplacedBy property of the Resource type
as the basis for extension type, ResourceReference
as the basis for extension type, VersionRelease
as the basis for extension type, BibliographicReference

Properties:

Property of the RelatedResource type
@id
What it represents:
an identifier for the reference
Value type:
text
Property of the RelatedResource type
@type
What it represents:
Value type:
text or list of text values
Property of the RelatedResource type
title
What it represents:
the name of the resource being referenced
Value type:
text
Property of the RelatedResource type
proxyFor
What it represents:
a local identifier representing this resource
Value type:
text (URL)
Property of the RelatedResource type
location
What it represents:
the URL for accessing the resource
Value type:
text (URL)
Property of the RelatedResource type
label
What it represents:
a recommended label or title to display as the text for a link to the document
Value type:
text
Property of the RelatedResource type
issued
What it represents:
The date the referenced resource was issued
Value type:
FlexibleDate object
Property of the RelatedResource type
description
What it represents:
a brief, human-readable description of what this reference refers to and/or why it is being referenced.
Value type:
text

Named Type
ResourceReference

JSON type:
object
What it represents:
a reference to another resource that may have an associated ID
Where it is used:
as a value type for the isPartOf property in the Resource type
as the basis for extension type, IncludedResource
as the basis for extension type, Affiliation

Properties:

Inherited from RelatedResource:
@id, @type, title, proxyFor, location, label, issued, description

Named Type
VersionRelease

JSON type:
object
What it represents:
notes about a versioned release of the resource
Where it is used:
as a value type for the versionHistory list property of the Resource type

Properties:

Inherited from RelatedResource:
@id, @type, title, proxyFor, location, label, issued, description
Property of the VersionRelease type
version
What it represents:
a string indicating a version of the release of this resource
Value type:
text

Named Type
BibliographicReference

JSON type:
object
What it represents:
a reference to a creative work that provides information or data that is important to this resource.
Where it is used:
as a value type for the references list property of the Resource type
as the basis for extension type, DCiteReference

Properties:

Inherited from RelatedResource:
@id, @type, title, proxyFor, location, label, issued, description
Property of the BibliographicReference type
citation
What it represents:
a full formated citation string for the reference, appropriate for inclusion in a bibliography
Value type:
text
Property of the BibliographicReference type
refType
What it represents:
the type of relationship that this document has with the resource
Value type:
text

Named Type
DCiteReference

JSON type:
object
What it represents:
a bibliographical reference with a controlled vocabulary for its reference type (refType)
Where it is used:
as an allowed value type in the references property in the Resource type

Properties:

Inherited from RelatedResource:
@id, @type, title, proxyFor, location, label, issued, description
Inherited from BibliographicReference:
citation, refType
Property of the DCiteReference type
refType
What it represents:
a term indicating the nature of the relationship between this resource and the one being referenced
Value type:
text
Allowed Values:
IsDocumentedBy
The referenced document provides documentation of this resource.
IsSupplementedTo
The referenced document is a supplement to this resource.
IsCitedBy
The referenced document cites the resource in some way.
Cites
This resource cites the referenced document.
IsReviewedBy
The referenced document reviews this resource.
IsReferencedBy
The resource is used as a source of information by the referenced document.
References
The referenced document is used as a source of information by the resource.
IsSourceOf
The resource is the source of upon which the referenced resource is based.
IsDerivedFrom
The referenced document is the source upon which the resource is based.
IsNewVersionOf
The referenced resource is a previous version of this resource.
IsPreviousVersionOf
The referenced resource is a newer version of this resource.
IsVariantOf
The referenced resource contains the content of this resource in a different form.

Named Type
ISO8601DateRange

JSON type:
text
What it represents:
a single date-time, a date range, or a periodic time interval compliant with the ISO 8601 standard for date-times and intervals

The format of the value is restricted to 3 forms. A single date has the form YYYY-MM-DDThh:mm:ss.sTZD, as in "2017-03-24T03:45:33.1"; note that any lowere precision version of this form is acceptable, such as "2017-03-24" or "2017".

A date range is expressed with two single dates in the above form separated by a forward slash (/)--as, in "2016-01/2016-12"

The third form from indicates a periodic interval, used to indicate that a resource is updated on a regular basis. Examples include "R/P1D" for daily, "R5/P2W" for 5 times, every 2 weeks. Consult the ISO 8601 standard for the detailed syntax.
Where it is used:
as a value type for the modified property in the Resource type

Named Type
Topic

JSON type:
object
What it represents:
a container for an identified concept term or proper thing
Where it is used:
as a value type for the topic list property of the Resource type
as a value type for the topic list property of the Component type
as a value type for the algorithm property in the Checksum type

Properties:

Property of the Topic type
@type
What it represents:
a label indicating whether the value refers to a concept or a thing
Value type:
text
Allowed Values:
Concept
label indicating that the value refers to a concept (as in owl:Concept)
Thing
label indicating that the value refers to a named person, place, or thing (as in skos:Thing)
Property of the Topic type
scheme
What it represents:
a URI that identifies the controlled vocabulary, registry, or identifier system that the value is defined in.
Value type:
text (URL)
Property of the Topic type
@id
What it represents:
the unique identifier identifying the concept or thing
Value type:
text (URL)
Property of the Topic type
tag
What it represents:
a short, display-able token that locally represents the concept or thing
Value type:
text

Named Type
Organization

JSON type:
object
What it represents:
a named organization that may be part of a larger organization
Where it is used:
as a value type for the publisher property in the Resource type
as a value type for the subOrganizationOf property in the Organization type

Properties:

Property of the Organization type
@type
What it represents:
IRI for the JSON-LD data type. This should be org:Organization for each publisher
Value type:
text
Property of the Organization type
name
What it represents:
The plain-text name of the organization
Value type:
text
Property of the Organization type
subOrganizationOf
What it represents:
A parent organizational entity
Value type:
Organization object

Named Type
ContactInfo

JSON type:
object
What it represents:
Information describing various ways to contact an entity
Where it is used:
as a value type for the contactPoint property in the Resource type

Properties:

Property of the ContactInfo type
@type
What it represents:
Value type:
text
Property of the ContactInfo type
fn
What it represents:
full name of the contact person, role, or organization
Value type:
text
Property of the ContactInfo type
hasEmail
What it represents:
The email address of the resource contact
Value type:
text
Property of the ContactInfo type
postalAddress
What it represents:
the contact mailing address
Value type:
PostalAddress object
Property of the ContactInfo type
phoneNumber
What it represents:
the contact telephone number
Value type:
text
Property of the ContactInfo type
timezone
What it represents:
the time zone where the contact typically operates
Value type:
text
Property of the ContactInfo type
proxyFor
What it represents:
a local identifier representing this person
Value type:
text (URL)

Named Type
PostalAddress

JSON type:
list of text values
What it represents:
a line-delimited listing of a postal address
Where it is used:
as a value type for the postalAddress property in the ContactInfo type

Named Type
Identifier

JSON type:
object
What it represents:
a complete description of an identifier, including the scheme that it adheres to
Where it is used:

Properties:

Property of the Identifier type
scheme
What it represents:
a label indicating the system that the identifier adheres to
Value type:
text
Property of the Identifier type
value
What it represents:
the value of the identifier
Value type:
text

Named Type
Checksum

JSON type:
object
What it represents:
a checksum with its algorithm noted
Where it is used:
as a value type for the checksum property in the DownloadableFile type

Properties:

Property of the Checksum type
algorithm
What it represents:
the algorithm used to produce the checksum hash
Value type:
Topic object
Property of the Checksum type
hash
What it represents:
the checksum value
Value type:
text

Named Type
Format

JSON type:
object
What it represents:
a description of a file format that a file employs
Where it is used:
as a value type for the format property in the DownloadableFile type
as a value type for the format property in the AccessPage type

Properties:

Property of the Format type
description
What it represents:
a human-readable description of the format
Value type:
text
Property of the Format type
scheme
What it represents:
a URI that identifies the format type registry or identification system that the value is defined in.
Value type:
text (URL)
Property of the Format type
@id
What it represents:
the unique identifier for the format
Value type:
text (URL)
Property of the Format type
tag
What it represents:
a short, display-able token or abbreviation for the format
Value type:
text

Named Type
Person

JSON type:
object
What it represents:
an identification a Person contributing to the publication of a resource
Where it is used:
as a value type for the authors list property of the DataPublication type

Properties:

Property of the Person type
@type
What it represents:
the class indicating that this is a Person
Value type:
text
Property of the Person type
fn
What it represents:
the author's full name in the preferred format
Value type:
text
Property of the Person type
givenName
What it represents:
the author's given name
Value type:
text
Property of the Person type
familyName
What it represents:
the author's family name
Value type:
text
Property of the Person type
middleName
What it represents:
the author's middle names or initials
Value type:
text
Property of the Person type
orcid
What it represents:
the author's ORCID
Value type:
ORCIDpath object
Property of the Person type
affiliation
What it represents:
The institution the person was affiliated with at the time of publication
Value type:
list of Affiliation objects
Property of the Person type
proxyFor
What it represents:
a local identifier representing this person
Value type:
text (URL)

Named Type
ORCIDpath

JSON type:
text
What it represents:
the format of the path portion of an ORCID identifier (i.e. without the preceding resolver URL base)
Where it is used:
as a value type for the orcid property in the Person type

Named Type
Affiliation

JSON type:
object
What it represents:
a description of an organization that a person is a member of
Where it is used:
as an allowed value type in the isPartOf property in the Resource type
as a value type for the affiliation list property of the Person type

Properties:

Inherited from RelatedResource:
@id, @type, title, proxyFor, location, label, issued, description
Property of the Affiliation type
subunits
What it represents:
sub-units of the main organization the that the person is a member of
Value type:
list of text values

Glossary

JSON
a text-based, machine-readable data format (whose abbreviated name stands for Javascript Object Notation). JSON is particulary well-suited for encoding metadata because its central data type, the object, collects data into a set of name-value pairs (referred to as the object's properties).

named type
The schema defines the value type of each metadata property. The schema can customize restrictions on what values the property can have. The restrictions are often defined as a custom type and given a name, making it a named type.

As an example, a property providing contact information is called contactPoint. Its value is a set of sub-properties that includes fn (full name), hasEmail (an email address), phoneNumber, etc. The set of subproperties that is collectively the contact information is a type called ContactInfo.

property
A property is a piece of metadata that has a name and a value. A value can take the form of a simple value like text, a number, or true/false. It can a also be list of values of those simple types, or it can be a set of "sub-" properties, each with their own name and value.

value type
The value type of a property restricts the kind value it can have. In general, a property can be defined to have one of the following types of JSON values:
  • text (i.e. a string),
  • a number (e.g. integer or decimal),
  • a boolean (true or false),
  • a collection sub-properties (an object), or
  • a list (i.e. an array) of any of the above types.
Further restrictions can be put on the values, such as,
  • a text value being restricted to one of a list of allowed values,
  • a text value being restricted to a particular format, like that of a URL,
  • a number value being restricted to a particular range,
  • an object with properties having specific names (and value types).
A special restriction on a value type are usually specified in the schema and given a name; making it a named type.

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