JSON-LD 1.0

http://www.w3.org/TR/2013/CR-json-ld-20130910 Archived on 2026-04-24 10:25 UTC

JSON-LD 1.0
JSON-LD 1.0
A JSON-based Serialization for Linked Data
W3C
Candidate Recommendation
10 September 2013
This version:
Latest published version:
Latest editor's draft:
Previous version:
Editors:
Manu Sporny
Digital Bazaar
Gregg Kellogg
Kellogg Associates
Markus Lanthaler
Graz University of Technology
Authors:
Manu Sporny
Digital Bazaar
Dave Longley
Digital Bazaar
Gregg Kellogg
Kellogg Associates
Markus Lanthaler
Graz University of Technology
Niklas Lindström
This document is also available in this non-normative format:
diff to previous version
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Abstract
JSON is a useful data serialization and messaging format.
This specification defines JSON-LD, a JSON-based format to serialize
Linked Data. The syntax is designed to easily integrate into deployed
systems that already use JSON, and provides a smooth upgrade path from
JSON to JSON-LD.
It is primarily intended to be a way to use Linked Data in Web-based
programming environments, to build interoperable Web services, and to
store Linked Data in JSON-based storage engines.
Status of This Document
This section describes the status of this document at the time of its publication. Other
documents may supersede this document. A list of current
W3C
publications and the latest revision
of this technical report can be found in the
W3C
technical reports
index
at http://www.w3.org/TR/.
This document has been under development for over 30 months in the
JSON for Linking Data Community Group. The document has been
transferred to the RDF Working Group for review, improvement, and publication.
The specification has undergone significant development, review, and changes
during the course of the last 30 months.
There are several independent
interoperable implementations
of
this specification. There is a fairly complete test suite [
JSON-LD-TESTS
and a
live JSON-LD editor
that is capable of demonstrating the features described in
this document. While development on implementations, the test suite
and the live editor will continue, they are believed to be mature enough
to be integrated into a non-production system at this point in time with
the expectation that they could be used in a production system within the
next three months.
The following features are at risk and may be removed:
Support for
@base: null
Confusion related to context-sensitivity of
@type
Lists of lists and partial list conversion from RDF
Allow blank nodes to be used as properties
Changes since the
11 April 2013 Last Call Working Draft
Allow keyword aliases to be defined using expanded term definitions
Mention profile URIs also in the sections describing the various document forms
Support relative IRIs in
@base
Clarify how the
profile
media type parameter is used in the content
negotiation process
Update grammar to disallow blank nodes as data types
Update grammar to allow blank node identifiers as value of
@vocab
Align the JSON-LD Data Model with the RDF Data Model
Support processing of documents with a
+json
media type as defined in
RFC6839
Added a brief description of the data model to the introduction.
Fixed a number of document readability and flow issues related to all
of the updates made over the last several moths.
This document was published by the
RDF Working Group
as a Candidate Recommendation.
This document is intended to become a
W3C
Recommendation.
If you wish to make comments regarding this document, please send them to
public-rdf-comments@w3.org
archives
).
W3C
publishes a Candidate Recommendation to indicate that the document is believed
to be stable and to encourage implementation by the developer community. This
Candidate Recommendation is expected to advance to Proposed Recommendation no earlier than
01 October 2013.
All comments are welcome.
Publication as a Candidate Recommendation does not imply endorsement by the
W3C
Membership.
This is a draft document and may be updated, replaced or obsoleted by other documents at
any time. It is inappropriate to cite this document as other than work in progress.
Before this specification may exit the Candidate Recommendation phase,
at least two independent implementations must pass each test,
although no single implementation must pass every test. The
working group will decide when
the test suite is of sufficient quality to test interoperability and
will produce an implementation report hosted together with the test suite.
This document was produced by a group operating under the
5 February 2004
W3C
Patent Policy
W3C
maintains a
public list of any patent disclosures
made in connection with the deliverables of the group; that page also includes instructions for
disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains
Essential Claim(s)
must disclose the
information in accordance with
section
6 of the
W3C
Patent Policy
Table of Contents
1.
Introduction
1.1
How to Read this Document
2.
Design Goals and Rationale
3.
Terminology
3.1
General Terminology
3.2
Data Model Overview
3.3
Syntax Tokens and Keywords
4.
Conformance
5.
Basic Concepts
5.1
The Context
5.2
IRIs
5.3
Node Identifiers
5.4
Specifying the Type
6.
Advanced Concepts
6.1
Base
IRI
6.2
Default Vocabulary
6.3
Compact IRIs
6.4
Typed Values
6.5
Type Coercion
6.6
Embedding
6.7
Advanced Context Usage
6.8
Interpreting JSON as JSON-LD
6.9
String Internationalization
6.10
IRI
Expansion within a Context
6.11
Sets and Lists
6.12
Reverse Properties
6.13
Named Graphs
6.14
Identifying Blank Nodes
6.15
Aliasing Keywords
6.16
Data Indexing
6.17
Expanded Document Form
6.18
Compacted Document Form
6.19
Flattened Document Form
6.20
Embedding JSON-LD in HTML Documents
7.
Data Model
8.
JSON-LD Grammar
8.1
8.2
Node Objects
8.3
Value Objects
8.4
Lists and Sets
8.5
Language Maps
8.6
Index Maps
8.7
Context Definitions
9.
Relationship to RDF
9.1
Serializing/Deserializing RDF
A.
Relationship to Other Linked Data Formats
A.1
Turtle
A.2
RDFa
A.3
Microformats
A.4
Microdata
B.
IANA Considerations
C.
Acknowledgements
D.
References
D.1
Normative references
D.2
Informative references
1.
Introduction
This section is non-normative.
Linked Data [
LINKED-DATA
] is a way to create a network of
standards-based machine interpretable data across different documents and
Web sites. It allows an application to start at one piece of Linked Data,
and follow embedded links to other pieces of Linked Data that are hosted on
different sites across the Web.
JSON-LD is a lightweight syntax to serialize Linked Data in
JSON [
RFC4627
]. Its design allows existing JSON to be interpreted as
Linked Data with minimal changes. JSON-LD is primarily intended to be a
way to use Linked Data in Web-based programming environments, to build
interoperable Web services, and to store Linked Data in JSON-based storage engines. Since
JSON-LD is 100% compatible with JSON, the large number of JSON parsers and libraries
available today can be reused. In addition to all the features JSON provides,
JSON-LD introduces:
a universal identifier mechanism for
JSON objects
via the use of
IRIs
a way to disambiguate keys shared among different JSON documents by mapping
them to
IRIs
via a
context
a mechanism in which a value in a
JSON object
may refer
to a
JSON object
on a different site on the Web,
the ability to annotate
strings
with their language,
a way to associate datatypes with values such as dates and times,
and a facility to express one or more directed graphs, such as a social
network, in a single document.
JSON-LD is designed to be usable directly as JSON, with no knowledge of RDF
RDF11-CONCEPTS
]. It is also designed to be usable as RDF, if desired, for
use with other Linked Data technologies like SPARQL. Developers who
require any of the facilities listed above or need to serialize an RDF Graph
or RDF Dataset in a JSON-based syntax will find JSON-LD of interest. People
intending to use JSON-LD with RDF tools will find it can be used as another
RDF syntax, like Turtle [
TURTLE
]. Complete details of how JSON-LD relates
to RDF are in section
9.
Relationship to RDF
The syntax is designed to not disturb already
deployed systems running on JSON, but provide a smooth upgrade path from
JSON to JSON-LD. Since the shape of such data varies wildly, JSON-LD
features mechanisms to reshape documents into a deterministic structure
which simplifies their processing.
1.1
How to Read this Document
This section is non-normative.
This document is a detailed specification for a serialization of Linked
Data in JSON. The document is primarily intended for the following audiences:
Software developers who want to encode Linked Data in a variety of
programming languages that can use JSON
Software developers who want to convert existing JSON to JSON-LD
Software developers who want to understand the design decisions and
language syntax for JSON-LD
Software developers who want to implement processors and APIs for
JSON-LD
Software developers who want to generate or consume Linked Data,
an RDF graph, or an RDF Dataset in a JSON syntax
A companion document, the JSON-LD Processing Algorithms and API specification
JSON-LD-API
], specifies how to work with JSON-LD at a higher level by
providing a standard library interface for common JSON-LD operations.
To understand the basics in this specification you must first be familiar with
JSON, which is detailed in [
RFC4627
].
This document almost exclusively uses the term
IRI
Internationalized Resource Indicator
when discussing hyperlinks. Many Web developers are more familiar with the
URL (
Uniform Resource Locator
terminology. The document also uses, albeit rarely, the URI
Uniform Resource Indicator
terminology. While these terms are often used interchangeably among
technical communities, they do have important distinctions from one
another and the specification goes to great lengths to try and use the
proper terminology at all times.
2.
Design Goals and Rationale
This section is non-normative.
JSON-LD satisfies the following design goals:
Simplicity
No extra processors or software libraries are necessary to use JSON-LD
in its most basic form. The language provides developers with a very easy
learning curve. Developers only need to know JSON and two
keywords
@context
and
@id
) to use the basic functionality in JSON-LD.
Compatibility
A JSON-LD document is always a valid JSON document. This ensures that
all of the standard JSON libraries work seamlessly with JSON-LD documents.
Expressiveness
The syntax serializes directed graphs. This ensures that almost
every real world data model can be expressed.
Terseness
The JSON-LD syntax is very terse and human readable, requiring as
little effort as possible from the developer.
Zero Edits, most of the time
JSON-LD ensures a smooth and simple transition from existing
JSON-based systems. In many cases,
zero edits to the JSON document and the addition of one line to the HTTP response
should suffice (see
section 6.8 Interpreting JSON as JSON-LD
).
This allows organizations that have
already deployed large JSON-based infrastructure to use JSON-LD's features
in a way that is not disruptive to their day-to-day operations and is
transparent to their current customers. However, there are times where
mapping JSON to a graph representation is a complex undertaking.
In these instances, rather than extending JSON-LD to support
esoteric use cases, we chose not to support the use case. While Zero
Edits is a design goal, it is not always possible without adding
great complexity to the language. JSON-LD focuses on simplicity when
possible.
Usable as RDF
JSON-LD is usable by developers as
idiomatic JSON, with no need to understand RDF [
RDF11-CONCEPTS
].
JSON-LD is also usable as RDF, so people intending to use JSON-LD
with RDF tools will find it can be used like any other RDF syntax.
Complete details of how JSON-LD relates to RDF are in section
9.
Relationship to RDF
3.
Terminology
3.1
General Terminology
This document uses the following terms as defined in JSON [
RFC4627
]. Refer
to the
JSON Grammar
section in [
RFC4627
] for formal definitions.
JSON object
An object structure is represented as a pair of curly brackets surrounding
zero or more key-value pairs. A key is a
string
A single colon comes after each key, separating the key from the value.
A single comma separates a value from a following key. In contrast to JSON,
in JSON-LD the keys in an object must be unique.
array
An array structure is represented as square brackets surrounding zero
or more values. Values are separated by commas.
In JSON, an array is an
ordered
sequence of zero or more values.
While JSON-LD uses the same array representation as JSON,
the collection is
unordered
by default. While order is
preserved in regular JSON arrays, it is not in regular JSON-LD arrays
unless specifically defined (see
section 6.11 Sets and Lists
).
string
A string is a sequence of zero or more Unicode characters,
wrapped in double quotes, using backslash escapes (if necessary).
number
A number is similar to that used in most programming languages, except
that the octal and hexadecimal formats are not used and leading zeros
are not allowed.
true
and
false
Values that are used to express one of two possible boolean states.
null
The
null
value, which is typically used to clear or forget
data. For example, a key-value pair in the
@context
where the value is
null
explicitly
decouples a
term
's association with an
IRI
A key-value pair in the body of a JSON-LD document whose
value is
null
has the same meaning as if the key-value pair
was not defined. If
@value
@list
, or
@set
is set to
null
in expanded form, then
the entire
JSON object
is ignored.
3.2
Data Model Overview
This section is non-normative.
Generally speaking, the data model used for JSON-LD is a labeled,
directed
graph
. The graph contains
nodes
, which are connected by
edges
. A
node
is typically data
such as a
string
number
typed values
(like dates and times)
or an
IRI
There is also a special class of
node
called a
blank node
, which is typically used to express data that does
not have a global identifier like an
IRI
Blank nodes
are identified using a
blank node identifier
. This simple data model is incredibly
flexible and powerful, capable of modeling almost any kind of
data. For a deeper explanation of the data model, see
section
7.
Data Model
Developers who are familiar with Linked Data technologies will
recognize the data model as the RDF Data Model. To dive deeper into how
JSON-LD and RDF are related, see
section
9.
Relationship to RDF
3.3
Syntax Tokens and Keywords
JSON-LD specifies a number of syntax tokens and
keywords
that are a core part of the language:
@context
Used to define the short-hand names that are used throughout a JSON-LD
document. These short-hand names are called
and help
developers to express specific identifiers in a compact manner. The
@context
keyword is described in detail in
section 5.1 The Context
@id
Used to uniquely identify
things
that are being described in the document
with
IRIs
or
blank node identifiers
. This keyword
is described in
section 5.3 Node Identifiers
@value
Used to specify the data that is associated with a particular
property
in the graph. This keyword is described in
section 6.9 String Internationalization
and
section 6.4 Typed Values
@language
Used to specify the language for a particular string value or the default
language of a JSON-LD document. This keyword is described in
section 6.9 String Internationalization
@type
Used to set the data type of a
node
or
typed value
. This keyword is described in
section 6.4 Typed Values
@container
Used to set the default container type for a
term
This keyword is described in
section 6.11 Sets and Lists
@list
Used to express an ordered set of data.
This keyword is described in
section 6.11 Sets and Lists
@set
Used to express an unordered set of data and to ensure that values are always
represented as arrays. This keyword is described in
section 6.11 Sets and Lists
@reverse
Used to express reverse properties. This keyword is described in
section 6.12 Reverse Properties
@index
Used to specify that a container is used to index information and
that processing should continue deeper into a JSON data structure.
This keyword is described in
section 6.16 Data Indexing
@base
Used to set the base
IRI
against which
relative IRIs
are resolved. This keyword is described in
section 6.1 Base IRI
@vocab
Used to expand properties and values in
@type
with a common prefix
IRI
. This keyword is described in
section 6.2 Default Vocabulary
@graph
Used to express a
graph
This keyword is described in
section 6.13 Named Graphs
The separator for JSON keys and values that use
compact IRIs
All keys,
keywords
, and values in JSON-LD are case-sensitive.
4.
Conformance
This specification describes the conformance criteria for JSON-LD documents.
This criteria is relevant to authors and authoring tool implementers. As well
as sections marked as non-normative, all authoring guidelines, diagrams, examples,
and notes in this specification are non-normative. Everything else in this
specification is normative.
JSON-LD document
complies with this specification if it follows
the normative statements in appendix
8.
JSON-LD Grammar
. JSON documents
can be interpreted as JSON-LD by following the normative statements in
section 6.8 Interpreting JSON as JSON-LD
. For convenience, normative
statements for documents are often phrased as statements on the properties of the document.
The key words
MUST
MUST NOT
REQUIRED
SHALL
SHALL NOT
SHOULD
SHOULD NOT
RECOMMENDED
NOT RECOMMENDED
MAY
, and
OPTIONAL
in this specification have the
meaning defined in [
RFC2119
].
5.
Basic Concepts
This section is non-normative.
JSON [
RFC4627
] is a lightweight, language-independent data interchange format.
It is easy to parse and easy to generate. However, it is difficult to integrate JSON
from different sources as the data may contain keys that conflict with other
data sources. Furthermore, JSON has no
built-in support for hyperlinks, which are a fundamental building block on
the Web. Let's start by looking at an example that we will be using for the
rest of this section:
Example 1
: Sample JSON document
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/",
"image": "http://manu.sporny.org/images/manu.png"
It's obvious to humans that the data is about a person whose
name
is "Manu Sporny"
and that the
homepage
property contains the URL of that person's homepage.
A machine doesn't have such an intuitive understanding and sometimes,
even for humans, it is difficult to resolve ambiguities in such representations. This problem
can be solved by using unambiguous identifiers to denote the different concepts instead of
tokens such as "name", "homepage", etc.
Linked Data, and the Web in general, uses
IRIs
(Internationalized Resource Identifiers as described in [
RFC3987
]) for unambiguous
identification. The idea is to use
IRIs
to assign unambiguous identifiers to data that may be of use to other developers.
It is useful for
like
name
and
homepage
, to expand to
IRIs
so that developers don't accidentally step on each other's terms. Furthermore, developers and
machines are able to use this
IRI
(by using a web browser, for instance) to go to
the term and get a definition of what the term means. This process is known as
IRI
dereferencing.
Leveraging the popular
schema.org vocabulary
the example above could be unambiguously expressed as follows:
Example 2
: Sample JSON-LD document using full IRIs instead of terms
": "Manu Sporny",
":
{ "@id":
"http://manu.sporny.org/"
, ← The '@id' keyword means 'This value is an identifier that is an IRI'
":
{ "@id":
"http://manu.sporny.org/images/manu.png"
In the example above, every property is unambiguously identified by an
IRI
and all values
representing
IRIs
are explicitly marked as such by the
@id
keyword
. While this is a valid JSON-LD
document that is very specific about its data, the document is also overly verbose and difficult
to work with for human developers. To address this issue, JSON-LD introduces the notion
of a
context
as described in the next section.
5.1
The Context
This section is non-normative.
When two people communicate with one another, the conversation takes
place in a shared environment, typically called
"the context of the conversation". This shared context allows the
individuals to use shortcut terms, like the first name of a mutual friend,
to communicate more quickly but without losing accuracy. A context in
JSON-LD works in the same way. It allows two applications to use shortcut
terms to communicate with one another more efficiently, but without
losing accuracy.
Simply speaking, a
context
is used to map
to
IRIs
are case sensitive
and any valid
string
that is not a reserved JSON-LD
keyword
can be used as a
term
For the sample document in the previous section, a
context
would
look something like this:
Example 3
: Context for the sample document in the previous section
"@context":
"name": "http://schema.org/name",
← This means that 'name' is shorthand for 'http://schema.org/name'
"image": {
"@id": "http://schema.org/image",
← This means that 'image' is shorthand for 'http://schema.org/image'
"@type": "@id"
← This means that a string value associated with 'image' should be interpreted as an identifier that is an IRI
},
"homepage": {
"@id": "http://schema.org/url",
← This means that 'homepage' is shorthand for 'http://schema.org/url'
"@type": "@id"
← This means that a string value associated with 'homepage' should be interpreted as an identifier that is an IRI
As the
context
above shows, the value of a
term definition
can
either be a simple string, mapping the
term
to an
IRI
or a
JSON object
When a
JSON object
is associated with a term, it is called
an
expanded term definition
. The example above specifies that
the values of
image
and
homepage
, if they are
strings, are to be interpreted as
IRIs
Expanded term definitions
also allow terms to be used for
index maps
and to specify whether
array
values are to be
interpreted as
sets or lists
Expanded term definitions
may
be defined using
absolute
or
compact IRIs
as keys, which is
mainly used to associate type or language information with an
absolute
or
compact
IRI
Contexts
can either be directly embedded
into the document or be referenced. Assuming the context document in the previous
example can be retrieved at
it can be referenced by adding a single line and allows a JSON-LD document to
be expressed much more concisely as shown in the example below:
Example 4
: Referencing a JSON-LD context
"@context": "http://json-ld.org/contexts/person.jsonld",
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/",
"image": "http://manu.sporny.org/images/manu.png"
The referenced context not only specifies how the terms map to
IRIs
in the Schema.org vocabulary but also
specifies that string values associated with
the
homepage
and
image
property
can be interpreted as an
IRI
"@type": "@id"
see
section 5.2 IRIs
for more details). This information allows developers
to re-use each other's data without having to agree to how their data will interoperate
on a site-by-site basis. External JSON-LD context documents may contain extra
information located outside of the
@context
key, such as
documentation about the
declared in the
document. Information contained outside of the
@context
value
is ignored when the document is used as an external JSON-LD context document.
JSON documents can be interpreted as JSON-LD without having to be modified by
referencing a
context
via an HTTP Link Header
as described in
section 6.8 Interpreting JSON as JSON-LD
. It is also
possible to apply a custom context using the JSON-LD API [
JSON-LD-API
].
In
JSON-LD documents
contexts
may also be specified inline.
This has the advantage that documents can be processed even in the
absence of a connection to the Web. Ultimately, this is a modeling decision
and different use cases may require different handling.
Example 5
: In-line context definition
"@context":
"name": "http://schema.org/name",
"image": {
"@id": "http://schema.org/image",
"@type": "@id"
},
"homepage": {
"@id": "http://schema.org/url",
"@type": "@id"
},
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/",
"image": "http://manu.sporny.org/images/manu.png"
This section only covers the most basic features of the JSON-LD
Context. More advanced features related to the JSON-LD Context are covered
in section
6.
Advanced Concepts
5.2
IRIs
This section is non-normative.
IRIs
(Internationalized Resource Identifiers
RFC3987
]) are fundamental to Linked Data as that is how most
nodes
and
properties
are identified. In JSON-LD, IRIs may be represented as an
absolute
IRI
or a
relative
IRI
. An
absolute
IRI
is defined in [
RFC3987
] as containing a
scheme
along with
path
and optional
query
and
fragment
segments. A
relative
IRI
is an
IRI
that is relative to some other
absolute
IRI
In JSON-LD all
relative IRIs
are resolved
relative to the
base
IRI
string
is interpreted as an
IRI
when it is the
value of an
@id
member:
Example 6
: Values of @id are interpreted as IRI
...
"homepage": { "
@id
": "http://example.com/" }
...
Values that are interpreted as
IRIs
, can also be
expressed as
relative IRIs
. For example,
assuming that the following document is located at
, the
relative
IRI
../
would expand to
(for more
information on where
relative IRIs
can be
used, please refer to section
8.
JSON-LD Grammar
).
Example 7
: IRIs can be relative
...
"homepage": { "
@id
": "../" }
...
Absolute IRIs
can be expressed directly
in the key position like so:
Example 8
: IRI as a key
...
": "Manu Sporny",
...
In the example above, the key
is interpreted as an
absolute
IRI
Term-to-
IRI
expansion occurs if the key matches a
term
defined
within the
active context
Example 9
: Term expansion from context definition
@context
":
name
": "
},
name
": "Manu Sporny",
"status": "trollin'"
JSON keys that do not expand to an
IRI
, such as
status
in the example above, are not Linked Data and thus ignored when processed.
If type
coercion
rules are specified in the
@context
for
a particular
term
or property
IRI
, an
IRI
is generated:
Example 10
: Type coercion
"@context":
...
"homepage":
"@id": "http://schema.org/url",
"@type": "@id"
...
...
"homepage": "http://manu.sporny.org/",
...
In the example above, since the value
is expressed as a JSON
string
, the type
coercion
rules will transform the value into an
IRI
when processing the data.
See
section 6.5 Type Coercion
for more
details about this feature.
In summary,
IRIs
can be expressed in a variety of
different ways in JSON-LD:
JSON object
keys that have a
term
mapping in
the
active context
expand to an
IRI
(only applies outside of the
context definition
).
An
IRI
is generated for the
string
value specified using
@id
or
@type
An
IRI
is generated for the
string
value of any key for which there
are
coercion
rules that contain a
@type
key that is
set to a value of
@id
or
@vocab
This section only covers the most basic features associated with IRIs
in JSON-LD. More advanced features related to IRIs are covered in
section
6.
Advanced Concepts
5.3
Node Identifiers
This section is non-normative.
To be able to externally reference
nodes
in a
graph
, it is important that
nodes
have an identifier.
IRIs
are a fundamental concept of Linked Data, for
nodes
to be truly linked, dereferencing the
identifier should result in a representation of that
node
This may allow an application to retrieve further information about a
node
In JSON-LD, a
node
is identified using the
@id
keyword
Example 11
: Identifying a node
"@context":
...
"name": "http://schema.org/name"
},
"@id": "http://me.markus-lanthaler.com/"
"name": "Markus Lanthaler",
...
The example above contains a
node object
identified by the
IRI
This section only covers the most basic features associated with
node identifiers in JSON-LD. More advanced features related to
node identifiers are covered in section
6.
Advanced Concepts
5.4
Specifying the Type
This section is non-normative.
The type of a particular node can be specified using the
@type
keyword
. In Linked Data, types are uniquely
identified with an
IRI
Example 12
: Specifying the type for a node
...
"@id": "http://example.org/places#BrewEats",
@type
": "
",
...
A node can be assigned more than one type by using an
array
Example 13
: Specifying multiple types for a node
...
"@id": "http://example.org/places#BrewEats",
@type
":
[ "http://schema.org/Restaurant", "http://schema.org/Brewery" ],
...
The value of a
@type
key may also be a
term
defined in the
active context
Example 14
: Using a term to specify the type
"@context": {
...
"Restaurant": "http://schema.org/Restaurant",
"Brewery": "http://schema.org/Brewery"
"@id": "http://example.org/places#BrewEats",
"@type": [ "Restaurant", "Brewery" ]
...
This section only covers the most basic features associated with
types in JSON-LD. More advanced features related to
types are covered in section
6.
Advanced Concepts
6.
Advanced Concepts
JSON-LD has a number of features that provide functionality above and beyond
the core functionality described above. The following section describes this
advanced functionality in more detail.
6.1
Base
IRI
This section is non-normative.
JSON-LD allows
IRI
s to be specified in a relative form which is
resolved against the document base according
section 5.1 Establishing a Base URI
of [
RFC3986
]. The base
IRI
may be explicitly set with a
context
using the
@base
keyword.
For example, if a JSON-LD document was retrieved from
relative IRIs would resolve against that
IRI
Example 15
: Use a relative IRI as node identifier
"@context": {
"label": "http://www.w3.org/2000/01/rdf-schema#label"
},
"@id": ""
"label": "Just a simple document"
This document uses an empty
@id
, which resolves to the document base.
However, if the document is moved to a different location, the
IRI
would change.
To prevent this without having to use an
absolute
IRI
, a
context
may define a
@base
mapping, to overwrite the base
IRI
for the document.
Example 16
: Setting the document base in a document
"@context": {
"@base": "http://example.com/document.jsonld"
},
"@id": "",
"label": "Just a simple document"
Setting
@base
to
null
will prevent
relative IRIs
to be expanded to
absolute IRIs
Feature at Risk 10
: Support for @base: null
Note: This feature is
"at risk"
and may
be removed from this specification based on feedback. Please send feedback to
public-rdf-comments@w3.org
For the current status see
features "at risk" in JSON-LD 1.0
Unlike many other serialization formats, JSON-LD allows to specify that
there is no base
IRI
from within the document (by setting
@base
to
null
). The result is that the algorithm for establishing a base
IRI
as specified in
RFC3986 section 5.1
is overridden so relative IRIs remain relative IRIs even in the case that an
IRI
would be available in one of the outer layers (e.g., the
IRI
used to retrieve
the document or an application supplied base
IRI
). Based on implementer feedback,
the Working Group may decide to remove this feature from JSON-LD 1.0.
Please note that the
@base
will be ignored if used in
external contexts.
6.2
Default Vocabulary
This section is non-normative.
At times, all properties and types may come from the same vocabulary. JSON-LD's
@vocab
keyword allows an author to set a common prefix to be used
for all properties and types that do not match a
term
and are neither
compact
IRI
nor an
absolute
IRI
(i.e., they do
not contain a colon).
Example 17
: Using a common vocabulary prefix
"@context": {
"@vocab": "http://schema.org/"
"@id": "http://example.org/places#BrewEats",
"@type":
"Restaurant"
"name"
: "Brew Eats"
...
If
@vocab
is used but certain keys in an
object
should not be expanded using
the vocabulary
IRI
, a
term
can be explicitly set
to
null
in the
context
. For instance, in the
example below the
databaseId
member would not expand to an
IRI
Example 18
: Using the null keyword to ignore data
"@context":
"@vocab": "http://schema.org/",
"databaseId": null
},
"@id": "http://example.org/places#BrewEats",
"@type": "Restaurant",
"name": "Brew Eats",
"databaseId"
: "23987520"
6.3
Compact IRIs
This section is non-normative.
compact
IRI
is a way of expressing an
IRI
using a
prefix
and
suffix
separated by a colon (
).
The
prefix
is a
term
taken from the
active context
and is a short string identifying a
particular
IRI
in a JSON-LD document. For example, the
prefix
foaf
may be used as a short hand for the
Friend-of-a-Friend vocabulary, which is identified using the
IRI
. A developer may append
any of the FOAF vocabulary terms to the end of the prefix to specify a short-hand
version of the
absolute
IRI
for the vocabulary term. For example,
foaf:name
would be expanded to the
IRI
Example 19
: Prefix expansion
@context
":
foaf
": "
...
},
"@type": "
foaf:Person
foaf:name
": "Dave Longley",
...
In the example above,
foaf:name
expands to the
IRI
and
foaf:Person
expands
to
Prefixes
are expanded when the form of the value
is a
compact
IRI
represented as a
prefix:suffix
combination, the
prefix
matches a
term
defined within the
active context
, and the
suffix
does not begin with two
slashes (
//
). The
compact
IRI
is expanded by
concatenating the
IRI
mapped to the
prefix
to the (possibly empty)
suffix
. If the
prefix
is not defined in the
active context
or the suffix begins with two slashes (such as in
),
the value is interpreted as
absolute
IRI
instead. If the prefix is an
underscore (
), the value is interpreted as
blank node identifier
instead.
It's also possible to use compact IRIs within the context as shown in the
following example:
Example 20
: Using vocabularies
"@context":
"xsd": "http://www.w3.org/2001/XMLSchema#",
"foaf": "http://xmlns.com/foaf/0.1/"
"foaf:homepage"
: { "@type": "@id" },
"picture": { "@id":
"foaf:depiction"
, "@type": "@id" }
},
"@id": "http://me.markus-lanthaler.com/",
"@type": "foaf:Person",
"foaf:name": "Markus Lanthaler",
"foaf:homepage": "http://www.markus-lanthaler.com/",
"picture": "http://twitter.com/account/profile_image/markuslanthaler"
6.4
Typed Values
This section is non-normative.
A value with an associated type, also known as a
typed value
, is indicated by associating a value with
an
IRI
which indicates the value's type. Typed values may be
expressed in JSON-LD in three ways:
By utilizing the
@type
keyword
when defining
term
within a
@context
section.
By utilizing a
value object
By using a native JSON type such as
number
true
, or
false
The first example uses the
@type
keyword to associate a
type with a particular
term
in the
@context
Example 21
: Expanded term definition with type coercion
"@context":
"modified":
"@id": "http://purl.org/dc/terms/modified",
"@type": "http://www.w3.org/2001/XMLSchema#dateTime"
},
...
"@id": "http://example.com/docs/1",
"modified": "2010-05-29T14:17:39+02:00",
...
The
modified
key's value above is automatically type coerced to a
dateTime
value because of the information specified in the
@context
. A JSON-LD processor will interpret the example above
as follows:
Subject
Property
Value
Value Type
2010-05-29T14:17:39+02:00
The second example uses the expanded form of setting the type information
in the body of a JSON-LD document:
Example 22
: Expanded value with type
"@context":
"modified":
"@id": "http://purl.org/dc/terms/modified"
},
...
"modified":
"@value": "2010-05-29T14:17:39+02:00",
"@type": "http://www.w3.org/2001/XMLSchema#dateTime"
...
Both examples above would generate the value
2010-05-29T14:17:39+02:00
with the type
. Note that it is
also possible to use a
term
or a
compact
IRI
to
express the value of a type.
The
@type
keyword
is also used to associate a type
with a
node
. The concept of a
node type
and
value type
are different.
Generally speaking, a
node type
specifies the type of thing
that is being described, like a person, place, event, or web page. A
value type
specifies the data type of a particular value, such
as an integer, a floating point number, or a date.
Example 23
: Example demonstrating the context-sensitivity for @type
...
"@id": "http://example.org/posts#TripToWestVirginia",
"@type": "http://schema.org/BlogPosting"
, <- This is a node type
"modified":
"@value": "2010-05-29T14:17:39+02:00",
"@type": "http://www.w3.org/2001/XMLSchema#dateTime"
<- This is a value type
...
The first use of
@type
associates a
node type
) with the
node
which is expressed using the
@id
keyword
The second use of
@type
associates a
value type
) with the
value expressed using the
@value
keyword
. As a
general rule, when
@value
and
@type
are used in
the same
JSON object
, the
@type
keyword
is expressing a
value type
Otherwise, the
@type
keyword
is expressing a
node type
. The example above expresses the following data:
Subject
Property
Value
Value Type
2010-05-29T14:17:39+02:00
6.5
Type Coercion
This section is non-normative.
JSON-LD supports the coercion of values to particular data types.
Type
coercion
allows someone deploying JSON-LD to coerce the incoming or
outgoing values to the proper data type based on a mapping of data type
IRIs
to
. Using type coercion, value representation is preserved without requiring
the data type to be specified with each piece of data.
Type coercion is specified within an
expanded term definition
using the
@type
key. The value of this key expands to an
IRI
Alternatively, the
keywords
@id
or
@vocab
may be used
as value to indicate that within the body of a JSON-LD document, a
string
value of a
term
coerced to
@id
or
@vocab
is to be interpreted as an
IRI
. The difference between
@id
and
@vocab
is how values are expanded
to
absolute IRIs
@vocab
first tries to expand the value
by interpreting it as
term
. If no matching
term
is found in the
active context
, it tries to expand it as
compact
IRI
or
absolute
IRI
if there's a colon in the value; otherwise, it will expand the value using the
active context's
vocabulary mapping, if present, or by interpreting it
as
relative
IRI
. Values coerced to
@id
in contrast are expanded as
compact
IRI
or
absolute
IRI
if a colon is present; otherwise, they are interpreted
as
relative
IRI
or
compact IRIs
used as the value of a
@type
key may be defined within the same context. This means that one may specify a
term
like
xsd
and then use
xsd:integer
within the same
context definition.
The example below demonstrates how a JSON-LD author can coerce values to
typed values
and
IRIs
Example 24
: Expanded term definition with types
"@context":
"xsd": "http://www.w3.org/2001/XMLSchema#",
"name": "http://xmlns.com/foaf/0.1/name",
"age":
"@id": "http://xmlns.com/foaf/0.1/age",
"@type": "xsd:integer"
"homepage":
"@id": "http://xmlns.com/foaf/0.1/homepage",
"@type": "@id"
},
"@id": "http://example.com/people#john",
"name": "John Smith",
"age":
"41"
"homepage":
"http://personal.example.org/",
"http://work.example.com/jsmith/"
The example shown above would generate the following data.
Subject
Property
Value
Value Type
John Smith
41
IRI
IRI
Terms may also be defined using
absolute IRIs
or
compact IRIs
. This allows coercion rules
to be applied to keys which are not represented as a simple
term
For example:
Example 25
: Term definitions using compact and absolute IRIs
"@context":
"foaf": "http://xmlns.com/foaf/0.1/",
foaf:age
":
"@id": "http://xmlns.com/foaf/0.1/age"
"@type": "xsd:integer"
},
":
"@type": "@id"
},
"foaf:name": "John Smith",
foaf:age
": "41",
":
"http://personal.example.org/",
"http://work.example.com/jsmith/"
In this case the
@id
definition in the term definition is optional.
If it does exist, the
compact
IRI
or
IRI
representing
the term will always be expanded to
IRI
defined by the
@id
key—regardless of whether a prefix is defined or not.
Type coercion is always performed using the unexpanded value of the key. In the
example above, that means that type coercion is done looking for
foaf:age
in the
active context
and not for the corresponding, expanded
IRI
Feature at Risk 9
: Confusion related to context-sensitivity of @type
Note: This feature is
"at risk"
and may
be removed from this specification based on feedback. Please send feedback to
public-rdf-comments@w3.org
For the current status see
features "at risk" in JSON-LD 1.0
A number of JSON-LD document authors have been confused with the context
sensitivity of @type. When used in the context, it means
"coerce the string value associated with the term to the following datatype."
When used in the body of a document in a JSON-LD object that represents a
node in the graph, it means "the rdf:type of the subject identified by @id
is the one that is the value associated with the @type keyword". When used
in expanded literal form, it means "the datatype of the value associated with
@value is the value associated with the @type keyword". This shifting of usage
has led to confusion that may be easily remedied by reading a tutorial or
the specification. It may also be that further modifications for declaring a
datatype may be required, such as introducing a "@coerce" or "@literalType"
keyword. Implementors are asked to pay particular attention to the
feature and provide feedback on alternative ways to express the functionality
described above. The feature may remain in the specification as-is, or it may
be modified heavily after further implementation experience has been gathered.
Note
Keys in the context are treated as
for the purpose of
expansion and value coercion. At times, this may result in multiple representations for the same expanded
IRI
For example, one could specify that
dog
and
cat
both expanded to
Doing this could be useful for establishing different type coercion or language specification rules. It also allows a
compact
IRI
(or even an
absolute
IRI
) to be defined as something else entirely. For example, one could specify that
the
term
should expand to
, but this usage is discouraged because it would lead to a
great deal of confusion among developers attempting to understand the JSON-LD document.
6.6
Embedding
This section is non-normative.
Embedding
is a JSON-LD feature that allows an author to
use
node objects
as
property
values. This is a commonly used mechanism for
creating a parent-child relationship between two
nodes
The example shows two nodes related by a property from the first node:
Example 26
: Embedding a node object as property value of another node object
...
"name": "Manu Sporny",
knows
":
@type
": "
Person
",
name
": "
Gregg Kellogg
",
...
node object
, like the one used above, may be used in
any value position in the body of a JSON-LD document.
6.7
Advanced Context Usage
This section is non-normative.
Section
5.1
The Context
introduced the basics of what makes
JSON-LD work. This section expands on the basic principles of the
context
and demonstrates how more advanced use cases can
be achieved using JSON-LD.
In general, contexts may be used at any time a
JSON object
is defined. The only time that one cannot
express a context is inside a context definition itself. For example, a
JSON-LD document
may use more than one context at different
points in a document:
Example 27
: Using multiple contexts
"@context": "http://example.org/contexts/person.jsonld",
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/",
"depiction": "http://twitter.com/account/profile_image/manusporny"
},
"@context": "http://example.org/contexts/place.jsonld",
"name": "The Empire State Building",
"description": "The Empire State Building is a 102-story landmark in New York City.",
"geo": {
"latitude": "40.75",
"longitude": "73.98"
Duplicate context
are overridden using a
most-recently-defined-wins mechanism.
Example 28
: Scoped contexts within node objects
"@context":
"name": "http://example.com/person#name,
"details": "http://example.com/person#details"
}"
name
": "Markus Lanthaler",
...
"details":
"@context":
"name": "http://example.com/organization#name"
name
": "Graz University of Technology"
In the example above, the
name
term
is overridden
in the more deeply nested
details
structure. Note that this is
rarely a good authoring practice and is typically used when working with
legacy applications that depend on a specific structure of the
JSON object
. If a
term
is redefined within a
context, all previous rules associated with the previous definition are
removed. If a
term
is redefined to
null
the
term
is effectively removed from the list of
defined in the
active context
Multiple contexts may be combined using an
array
, which is processed
in order. The set of contexts defined within a specific
JSON object
are
referred to as
local contexts
. The
active context
refers to the accumulation of
local contexts
that are in scope at a
specific point within the document. Setting a
local context
to
null
effectively resets the
active context
to an empty context. The following example specifies an external context
and then layers an embedded context on top of the external context:
Example 29
: Combining external and local contexts
"@context": [
"http://json-ld.org/contexts/person.jsonld",
"pic": "http://xmlns.com/foaf/0.1/depiction"
],
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/",
"pic": "http://twitter.com/account/profile_image/manusporny"
Note
When possible, the
context
definition should be put
at the top of a JSON-LD document. This makes the document easier to read and
might make streaming parsers more efficient. Documents that do not have the
context
at the top are still conformant JSON-LD.
Note
To avoid forward-compatibility issues,
starting with an
character are to be avoided as they
might be used as
keywords
in future versions
of JSON-LD. Terms starting with an
character that are not
JSON-LD 1.0 keywords
are treated as any other term, i.e.,
they are ignored unless mapped to an
IRI
. Furthermore, the use of
empty
""
) is not allowed as
not all programming languages are able to handle empty JSON keys.
6.8
Interpreting JSON as JSON-LD
Ordinary JSON documents can be interpreted as JSON-LD by referencing a JSON-LD
context
document in an HTTP Link Header. Doing so allows JSON to
be unambiguously machine-readable without requiring developers to drastically
change their documents and provides an upgrade path for existing infrastructure
without breaking existing clients that rely on the
application/json
media type or a media type with a
+json
suffix as defined in
RFC6839
].
In order to use an external context with an ordinary JSON document, an author
MUST
specify an
IRI
to a valid
JSON-LD document
in
an HTTP Link Header [
RFC5988
] using the
link relation. The referenced document
MUST
have a top-level
JSON object
The
@context
subtree within that object is added to the top-level
JSON object
of the referencing document. If an
array
is at the top-level of the referencing document and its items are
JSON objects
, the
@context
subtree is added to all
array
items. All extra information located outside
of the
@context
subtree in the referenced document
MUST
be
discarded. Effectively this means that the
active context
is
initialized with the referenced external
context
. A response
MUST NOT
contain more than one HTTP Link Header [
RFC5988
] using the
link relation.
The following example demonstrates the use of an external context with an
ordinary JSON document:
Example 30
: Referencing a JSON-LD context from a JSON document via an HTTP Link Header
GET /ordinary-json-document.json HTTP/1.1
Host: example.com
Accept: application/ld+json,application/json,*/*;q=0.1

====================================

HTTP/1.1 200 OK
...
Content-Type:
application/json
Link: ; rel="http://www.w3.org/ns/json-ld#context"; type="application/ld+json"
"name": "Markus Lanthaler",
"homepage": "http://www.markus-lanthaler.com/",
"image": "http://twitter.com/account/profile_image/markuslanthaler"
Please note that
JSON-LD documents
served with the
application/ld+json
media type
MUST
have all context information, including references to external
contexts, within the body of the document. Contexts linked via a
HTTP Link Header
MUST
be
ignored for such documents.
6.9
String Internationalization
This section is non-normative.
At times, it is important to annotate a
string
with its language. In JSON-LD this is possible in a variety of ways.
First, it is possible to define a default language for a JSON-LD document
by setting the
@language
key in the
context
Example 31
: Setting the default language of a JSON-LD document
"@context":
...
"@language": "ja"
"name":
"花澄"
"occupation":
"科学者"
The example above would associate the
ja
language
code with the two
strings
花澄
and
科学者
Languages codes are defined in [
BCP47
]. The default language applies to all
string
values that are not
type coerced
To clear the default language for a subtree,
@language
can
be set to
null
in a
local context
as follows:
Example 32
: Clearing default language
"@context": {
...
"@language": "ja"
},
"name": "花澄",
"details": {
"@context": {
"@language": null
"occupation": "Ninja"
Second, it is possible to associate a language with a specific
term
using an
expanded term definition
Example 33
: Expanded term definition with language
"@context": {
...
"ex": "http://example.com/vocab/",
"@language": "ja",
"name": { "@id": "ex:name",
"@language": null
},
"occupation": { "@id": "ex:occupation" },
"occupation_en": { "@id": "ex:occupation",
"@language": "en"
},
"occupation_cs": { "@id": "ex:occupation",
"@language": "cs"
},
"name": "Yagyū Muneyoshi",
"occupation": "忍者",
"occupation_en": "Ninja",
"occupation_cs": "Nindža",
...
The example above would associate
忍者
with the specified default
language code
ja
Ninja
with the language code
en
, and
Nindža
with the language code
cs
The value of
name
Yagyū Muneyoshi
wouldn't be
associated with any language code since
@language
was reset to
null
in the
expanded term definition
Note
Language associations are only applied to plain
strings
Typed values
or values that are subject to
type coercion
are not language tagged.
Just as in the example above, systems often need to express the value of a
property in multiple languages. Typically, such systems also try to ensure that
developers have a programmatically easy way to navigate the data structures for
the language-specific data. In this case,
language maps
may be utilized.
Example 34
: Language map expressing a property in three languages
"@context":
...
"occupation": { "@id": "ex:occupation",
"@container": "@language"
},
"name": "Yagyū Muneyoshi",
"occupation":
"ja": "忍者",
"en": "Ninja",
"cs": "Nindža"
...
The example above expresses exactly the same information as the previous
example but consolidates all values in a single property. To access the
value in a specific language in a programming language supporting dot-notation
accessors for object properties, a developer may use the
property.language
pattern. For example, to access the occupation
in English, a developer would use the following code snippet:
obj.occupation.en
Third, it is possible to override the default language by using a
value object
Example 35
: Overriding default language using an expanded value
"@context": {
...
"@language": "ja"
},
"name": "花澄",
"occupation":
"@value": "Scientist",
"@language": "en"
This makes it possible to specify a plain string by omitting the
@language
tag or setting it to
null
when expressing
it using a
value object
Example 36
: Removing language information using an expanded value
"@context": {
...
"@language": "ja"
},
"name":
"@value": "Frank"
"occupation": {
"@value": "Ninja",
"@language": "en"
},
"speciality": "手裏剣"
6.10
IRI
Expansion within a Context
This section is non-normative.
In general, normal
IRI
expansion rules apply
anywhere an
IRI
is expected (see
section 5.2 IRIs
). Within
context
definition, this can mean that terms defined
within the context may also be used within that context as long as
there are no circular dependencies. For example, it is common to use
the
xsd
namespace when defining
typed value
s:
Example 37
: IRI expansion within a context
"@context":
"xsd": "http://www.w3.org/2001/XMLSchema#"
"name": "http://xmlns.com/foaf/0.1/name",
"age":
"@id": "http://xmlns.com/foaf/0.1/age",
"@type":
"xsd:integer"
},
"homepage":
"@id": "http://xmlns.com/foaf/0.1/homepage",
"@type": "@id"
},
...
In this example, the
xsd
term
is defined
and used as a
prefix
for the
@type
coercion
of the
age
property.
may also be used when defining the
IRI
of another
term
Example 38
: Using a term to define the IRI of another term within a context
"@context":
"foaf": "http://xmlns.com/foaf/0.1/"
"xsd": "http://www.w3.org/2001/XMLSchema#",
"name":
"foaf:name"
"age":
"@id":
"foaf:age"
"@type": "xsd:integer"
},
"homepage":
"@id":
"foaf:homepage"
"@type": "@id"
},
...
Compact IRIs
and
IRIs
may be used on the left-hand side of a
term
definition.
Example 39
: Using a compact IRI as a term
"@context":
"foaf": "http://xmlns.com/foaf/0.1/"
"xsd": "http://www.w3.org/2001/XMLSchema#",
"name": "foaf:name",
foaf:age
":
"@type": "xsd:integer"
},
foaf:homepage
":
"@type": "@id"
},
...
In this example, the
compact
IRI
form is used in two different
ways.
In the first approach,
foaf:age
declares both the
IRI
for the
term
(using short-form) as well as the
@type
associated with the
term
. In the second
approach, only the
@type
associated with the
term
is
specified. The full
IRI
for
foaf:homepage
is determined by looking up the
foaf
prefix
in the
context
Absolute IRIs
may also be used in the key position in a
context
Example 40
: Associating context definitions with absolute IRIs
"@context":
"foaf": "http://xmlns.com/foaf/0.1/",
"xsd": "http://www.w3.org/2001/XMLSchema#",
"name": "foaf:name",
"foaf:age":
"@id": "foaf:age",
"@type": "xsd:integer"
},
":
"@type": "@id"
},
...
In order for the
absolute
IRI
to match above, the
absolute
IRI
needs to be used in the
JSON-LD document
. Also note that
foaf:homepage
will not use the
{ "@type": "@id" }
declaration because
foaf:homepage
is not the same as
That is,
are looked up in a
context
using
direct string comparison before the
prefix
lookup mechanism is applied.
Note
While it is possible to define a
compact
IRI
, or
an
absolute
IRI
to expand to some other unrelated
IRI
(for example,
foaf:name
expanding to
), such usage is strongly
discouraged.
The only exception for using terms in the
context
is that
circular definitions are not allowed. That is,
a definition of
term1
cannot depend on the
definition of
term2
if
term2
also depends on
term1
. For example, the following
context
definition
is illegal:
Example 41
: Illegal circular definition of terms within a context
"@context":
"term1": "term2:foo",
"term2": "term1:bar"
},
...
6.11
Sets and Lists
This section is non-normative.
A JSON-LD author can express multiple values in a compact way by using
arrays
. Since graphs do not describe ordering for links
between nodes, arrays in JSON-LD do not provide an ordering of the
contained elements by default. This is exactly the opposite from regular JSON
arrays, which are ordered by default. For example, consider the following
simple document:
Example 42
: Multiple values with no inherent order
...
"@id": "http://example.org/people#joebob",
"nick":
[ "joe", "bob", "JB" ]
...
The example shown above would result in the following data being generated,
each relating the node to an individual value, with no inherent order:
Subject
Property
Value
joe
bob
JB
Multiple values may also be expressed using the expanded form:
Example 43
: Using an expanded form to set multiple values
"@id": "http://example.org/articles/8",
"dc:title":
"@value": "Das Kapital",
"@language": "de"
},
"@value": "Capital",
"@language": "en"
The example shown above would generate the following data, again with
no inherent order:
Subject
Property
Value
Language
Das Kapital
de
Capital
en
As the notion of ordered collections is rather important in data
modeling, it is useful to have specific language support. In JSON-LD,
a list may be represented using the
@list
keyword
as follows:
Example 44
: An ordered collection of values in JSON-LD
...
"@id": "http://example.org/people#joebob",
"foaf:nick":
"@list": [ "joe", "bob", "jaybee" ]
...
This describes the use of this
array
as being ordered,
and order is maintained when processing a document. If every use of a given multi-valued
property is a list, this may be abbreviated by setting
@container
to
@list
in the
context
Example 45
: Specifying that a collection is ordered in the context
"@context":
...
"nick":
"@id": "http://xmlns.com/foaf/0.1/nick",
"@container": "@list"
...
"@id": "http://example.org/people#joebob",
"nick":
[ "joe", "bob", "jaybee" ]
...
Note
List of lists are not allowed in this version of JSON-LD.
This decision was made due to the extreme amount of added complexity when
processing lists of lists.
Feature at Risk 4
: Lists of lists and partial list conversion from RDF
Note: This feature is
"at risk"
and may
be removed from this specification based on feedback. Please send feedback to
public-rdf-comments@w3.org
For the current status see
features "at risk" in JSON-LD 1.0
The JSON-LD algorithms have been updated to support conversion of lists
of lists to
list objects
by preserving
the blank node head of the inner list. Lists of lists can, however, not be
represented directly in JSON-LD using the
@list
construct;
they have to be represented as a set of interlinked node objects using
RDF's rdf:first and rdf:rest properties. Implementors are asked to pay
particular attention to the feature and provide feedback on lists of lists
and partial lists. The feature may remain in the specification, or it may
be removed after further implementation experience has been gathered.
Similarly, partial list conversion in the RDF algorithms have been marked
as a feature at risk and may be removed from the specification based
on implementation feedback.
While
@list
is used to describe
ordered lists
the
@set
keyword is used to describe
unordered sets
The use of
@set
in the body of a JSON-LD document
is optimized away when processing the document, as it is just syntactic
sugar. However,
@set
is helpful when used within the context
of a document.
Values of terms associated with a
@set
or
@list
container
are always represented in the form of an
array
even if there is just a single value that would otherwise be optimized to
a non-array form in compact form (see
section 6.18 Compacted Document Form
). This makes post-processing of
JSON-LD documents easier as the data is always in array form, even if the
array only contains a single value.
6.12
Reverse Properties
This section is non-normative.
JSON-LD serializes directed
graphs
. That means that
every
property
points from a
node
to another
node
or
value
. However, in some cases, it is desirable
to serialize in the reverse direction. Consider for example the case where a person
and its children should be described in a document. If the used vocabulary does not
provide a
children
property
but just a
parent
property
, every
node
representing a child would have to
be expressed with a
property
pointing to the parent as in the following
example.
Example 46
: A document with children linking to their parent
"@id": "#homer"
"http://example.com/vocab#name": "Homer"
},
"@id": "#bart",
"http://example.com/vocab#name": "Bart",
"http://example.com/vocab#parent": { "@id": "#homer" }
},
"@id": "#lisa",
"http://example.com/vocab#name": "Lisa",
"http://example.com/vocab#parent": { "@id": "#homer" }
Expressing such data is much simpler by using JSON-LD's
@reverse
keyword
Example 47
: A person and its children using a reverse property
"@id": "#homer",
"http://example.com/vocab#name": "Homer",
"@reverse"
: {
"http://example.com/vocab#parent"
: [
"@id": "#bart",
"http://example.com/vocab#name": "Bart"
},
"@id": "#lisa",
"http://example.com/vocab#name": "Lisa"
The
@reverse
keyword
can also be used in
expanded term definitions
to create reverse properties as shown in the following example:
Example 48
: Using @reverse to define reverse properties
"@context": {
"name": "http://example.com/vocab#name",
"children": { "@reverse": "http://example.com/vocab#parent" }
},
"@id": "#homer",
"name": "Homer",
"children"
: [
"@id": "#bart",
"name": "Bart"
},
"@id": "#lisa",
"name": "Lisa"
6.13
Named Graphs
This section is non-normative.
At times, it is necessary to make statements about a
graph
itself, rather than just a single
node
. This can be done by
grouping a set of
nodes
using the
@graph
keyword
. A developer may also name data expressed using the
@graph
keyword
by pairing it with an
@id
keyword
as shown in the following example:
Example 49
: Identifying and making statements about a graph
"@context": {
"generatedAt": {
"@id": "http://www.w3.org/ns/prov#generatedAtTime",
"@type": "http://www.w3.org/2001/XMLSchema#date"
},
"Person": "http://xmlns.com/foaf/0.1/Person",
"name": "http://xmlns.com/foaf/0.1/name",
"knows": "http://xmlns.com/foaf/0.1/knows"
},
"@id": "http://example.org/graphs/73",
"generatedAt": "2012-04-09",
"@graph":
"@id": "http://manu.sporny.org/about#manu",
"@type": "Person",
"name": "Manu Sporny",
"knows": "http://greggkellogg.net/foaf#me"
},
"@id": "http://greggkellogg.net/foaf#me",
"@type": "Person",
"name": "Gregg Kellogg",
"knows": "http://manu.sporny.org/about#manu"
The example above expresses a
named graph
that is identified
by the
IRI
. That
graph is composed of the statements about Manu and Gregg. Metadata about
the graph itself is expressed via the
generatedAt
property,
which specifies when the graph was generated. An alternative view of the
information above is represented in table form below:
Graph
Subject
Property
Value
Value Type
2012-04-09
Manu Sporny
Gregg Kellogg
When a JSON-LD document's top-level structure is an
object
that contains no other
properties
than
@graph
and
optionally
@context
(properties that are not mapped to an
IRI
or a
keyword
are ignored),
@graph
is considered to express the otherwise implicit
default graph
. This mechanism can be useful when a number
of
nodes
exist at the document's top level that
share the same
context
, which is, e.g., the case when a
document is
flattened
. The
@graph
keyword collects such nodes in an
array
and allows the use of a shared context.
Example 50
: Using @graph to explicitly express the default graph
"@context": ...,
@graph
":
"@id": "http://manu.sporny.org/about#manu",
"@type": "foaf:Person",
"name": "Manu Sporny",
"knows": "http://greggkellogg.net/foaf#me"
},
"@id": "http://greggkellogg.net/foaf#me",
"@type": "foaf:Person",
"name": "Gregg Kellogg",
"knows": "http://manu.sporny.org/about#manu"
In this case, embedding doesn't work as each
node object
references the other. This is equivalent to using multiple
node objects
in array and defining
the
@context
within each
node object
Example 51
: Context needs to be duplicated if @graph is not used
"@context": ...,
"@id": "http://manu.sporny.org/about#manu",
"@type": "foaf:Person",
"name": "Manu Sporny",
"knows": "http://greggkellogg.net/foaf#me"
},
"@context": ...,
"@id": "http://greggkellogg.net/foaf#me",
"@type": "foaf:Person",
"name": "Gregg Kellogg",
"knows": "http://manu.sporny.org/about#manu"
6.14
Identifying Blank Nodes
This section is non-normative.
At times, it becomes necessary to be able to express information without
being able to uniquely identify the
node
with an
IRI
This type of node is called a
blank node
. JSON-LD does not require
all nodes to be identified using
@id
. However, some graph topologies
may require identifiers to be serializable. Graphs containing loops, e.g., cannot
be serialized using embedding alone,
@id
must be used to connect the nodes.
In these situations, one can use
blank node identifiers
which look like
IRIs
using an underscore (
as scheme. This allows one to reference the node locally within the document, but
makes it impossible to reference the node from an external document. The
blank node identifier
is scoped to the document in which it is used.
Example 52
: Specifying a local blank node identifier
...
"@id": "
_:n1
",
"name": "Secret Agent 1",
"knows":
"name": "Secret Agent 2",
"knows": { "@id": "
_:n1
" }
The example above contains information about to secret agents that cannot be identified
with an
IRI
. While expressing that
agent 1
knows
agent 2
is possible
without using
blank node identifiers
, it is
necessary assign
agent 1
an identifier so that it can be referenced from
agent 2
It is worth nothing that blank node identifiers may be relabeled during processing.
If a developer finds that they refer to the
blank node
more than once,
they should consider naming the node using a dereferenceable
IRI
so that
it can also be referenced from other documents.
6.15
Aliasing Keywords
This section is non-normative.
Each of the JSON-LD
keywords
except for
@context
, may be aliased to application-specific
keywords. This feature allows legacy JSON content to be utilized
by JSON-LD by re-using JSON keys that already exist in legacy documents.
This feature also allows developers to design domain-specific implementations
using only the JSON-LD
context
Example 53
: Aliasing keywords
"@context":
"url": "@id"
"a": "@type"
"name": "http://xmlns.com/foaf/0.1/name"
},
url
": "http://example.com/about#gregg",
": "http://xmlns.com/foaf/0.1/Person",
"name": "Gregg Kellogg"
In the example above, the
@id
and
@type
keywords
have been given the aliases
url
and
, respectively.
Since keywords cannot be redefined, they can also not be aliased to
other keywords.
6.16
Data Indexing
This section is non-normative.
Databases are typically used to make access to
data more efficient. Developers often extend this sort of functionality into
their application data to deliver similar performance gains. Often this
data does not have any meaning from a Linked Data standpoint, but is
still useful for an application.
JSON-LD introduces the notion of
index maps
that can be used to structure data into a form that is
more efficient to access. The data indexing feature allows an author to
structure data using a simple key-value map where the keys do not map
to
IRIs
. This enables direct access to data
instead of having to scan an array in search of a specific item.
In JSON-LD such data can be specified by associating the
@index
keyword
with a
@container
declaration in the context:
Example 54
: Indexing data in JSON-LD
"@context":
"schema": "http://schema.org/",
"name": "schema:name",
"body": "schema:articleBody",
"words": "schema:wordCount",
"post": {
"@id": "schema:blogPost",
"@container": "@index"
},
"@id": "http://example.com/",
"@type": "schema:Blog",
"name": "World Financial News",
"post": {
"en": {
"@id": "http://example.com/posts/1/en",
"body": "World commodities were up today with heavy trading of crude oil...",
"words": 1539
},
"de": {
"@id": "http://example.com/posts/1/de",
"body": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...",
"words": 1204
In the example above, the
blogPost
term
has
been marked as an
index map
. The
en
de
, and
ja
keys will be ignored
semantically, but preserved syntactically, by the JSON-LD Processor.
This allows a developer to access the German version
of the
blogPost
using the following code snippet:
obj.blogPost.de
The interpretation of the data above is expressed in
the table below. Note how the index keys do not appear in the Linked Data
below, but would continue to exist if the document were compacted or
expanded (see
section 6.18 Compacted Document Form
and
section 6.17 Expanded Document Form
) using a JSON-LD processor:
Subject
Property
Value
World Financial News
World commodities were up today with heavy trading of crude oil...
1539
Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...
1204
6.17
Expanded Document Form
This section is non-normative.
The JSON-LD Processing Algorithms and API specification [
JSON-LD-API
defines a method for
expanding
a JSON-LD document.
Expansion is the process of taking a JSON-LD document and applying a
@context
such that all IRIs, types, and values
are expanded so that the
@context
is no longer necessary.
For example, assume the following JSON-LD input document:
Example 55
: Sample JSON-LD document
"@context":
"name": "http://xmlns.com/foaf/0.1/name",
"homepage": {
"@id": "http://xmlns.com/foaf/0.1/homepage",
"@type": "@id"
},
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/"
Running the JSON-LD Expansion algorithm against the JSON-LD input document
provided above would result in the following output:
Example 56
: Expanded form for the previous example
"http://xmlns.com/foaf/0.1/name": [
{ "@value": "Manu Sporny" }
],
"http://xmlns.com/foaf/0.1/homepage": [
{ "@id": "http://manu.sporny.org/" }
JSON-LD's media type
defines a
profile
parameter which can be used to signal or request
expanded document form. The profile URI identifying expanded document
form is
6.18
Compacted Document Form
This section is non-normative.
The JSON-LD Processing Algorithms and API specification [
JSON-LD-API
] defines
a method for
compacting
a JSON-LD document. Compaction is the process
of applying a developer-supplied context to shorten
IRIs
to
or
compact IRIs
and JSON-LD values expressed in expanded form to simple values such as
strings
or
numbers
Often this makes it simpler to work with document as the data is expressed in
application-specific terms. Compacted documents are also typically easier to read
for humans.
For example, assume the following JSON-LD input document:
Example 57
: Sample expanded JSON-LD document
"http://xmlns.com/foaf/0.1/name": [ "Manu Sporny" ],
"http://xmlns.com/foaf/0.1/homepage": [
"@id": "http://manu.sporny.org/"
Additionally, assume the following developer-supplied JSON-LD context:
Example 58
: Sample context
"@context": {
"name": "http://xmlns.com/foaf/0.1/name",
"homepage": {
"@id": "http://xmlns.com/foaf/0.1/homepage",
"@type": "@id"
Running the JSON-LD Compaction algorithm given the context supplied above
against the JSON-LD input document provided above would result in the following
output:
Example 59
: Compact form of the sample document once sample context has been applied
"@context": {
"name": "http://xmlns.com/foaf/0.1/name",
"homepage": {
"@id": "http://xmlns.com/foaf/0.1/homepage",
"@type": "@id"
},
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/"
JSON-LD's media type
defines a
profile
parameter which can be used to signal or request
compacted document form. The profile URI identifying compacted document
form is
6.19
Flattened Document Form
This section is non-normative.
The JSON-LD Processing Algorithms and API specification [
JSON-LD-API
] defines
a method for
flattening
a JSON-LD document. Flattening collects all
properties of a
node
in a single
JSON object
and labels
all
blank nodes
with
blank node identifiers
This ensures a shape of the data and consequently may drastically simplify the code
required to process JSON-LD in certain applications.
For example, assume the following JSON-LD input document:
Example 60
: Sample JSON-LD document
"@context": {
"name": "http://xmlns.com/foaf/0.1/name",
"knows": "http://xmlns.com/foaf/0.1/knows"
},
"@id": "http://me.markus-lanthaler.com/",
"name": "Markus Lanthaler",
"knows": [
"@id": "http://manu.sporny.org/about#manu",
"name": "Manu Sporny"
},
"name": "Dave Longley"
Running the JSON-LD Flattening algorithm against the JSON-LD input document in
the example above and using the same context would result in the following
output:
Example 61
: Flattened and compacted form for the previous example
"@context": {
"name": "http://xmlns.com/foaf/0.1/name",
"knows": "http://xmlns.com/foaf/0.1/knows"
},
"@graph": [
"@id": "_:b0",
"name": "Dave Longley"
},
"@id": "http://manu.sporny.org/about#manu",
"name": "Manu Sporny"
},
"@id": "http://me.markus-lanthaler.com/",
"name": "Markus Lanthaler",
"knows": [
{ "@id": "http://manu.sporny.org/about#manu" },
{ "@id": "_:b0" }
JSON-LD's media type
defines a
profile
parameter which can be used to signal or request
flattened document form. The profile URI identifying flattened document
form is
. It can be
combined with the profile URI identifying
expanded document form
or
compacted document from
6.20
Embedding JSON-LD in HTML Documents
This section is non-normative.
HTML script tags can be used to embed blocks of data in documents.
This way, JSON-LD content can be easily embedded in HTML by placing
it in a script element with the
type
attribute set to
application/ld+json
Example 62
: Embedding JSON-LD in HTML

Depending on how the HTML document is served, certain strings may need
to be escaped.
Defining how such data may be used is beyond the scope of this specification.
The embedded JSON-LD document might be extracted as is or, e.g., be
interpreted as RDF.
If JSON-LD content is extracted as RDF [
RDF11-CONCEPTS
], it should be expanded into an
RDF Dataset
using the
Deserialize JSON-LD to RDF Algorithm
JSON-LD-API
].
7.
Data Model
JSON-LD is a serialization format for Linked Data based on JSON.
It is therefore important to distinguish between the syntax, which is
defined by JSON in [
RFC4627
], and the
data model
which is
an extension of the RDF data model [
RDF11-CONCEPTS
]. The precise
details of how JSON-LD relates to the RDF data model are given in
section 9. Relationship to RDF
To ease understanding for developers unfamiliar with the RDF model, the
following summary is provided:
JSON-LD document
serializes a
generalized RDF Dataset
RDF11-CONCEPTS
], which is a collection of
graphs
that comprises exactly one
default graph
and zero or more
named graphs
The
default graph
does not have a name and
MAY
be empty.
Each
named graph
is a pair consisting of an
IRI
or
blank node identifier
(the
graph name
and a
graph
. Whenever practical, the
graph name
SHOULD
be an
IRI
graph
is a labeled directed graph, i.e., a set of
nodes
connected by
edges
Every
edge
has a direction associated with it and is labeled with
an
IRI
or a
blank node identifier
. Within the JSON-LD syntax
these edge labels are called
properties
Whenever practical, an
edge
SHOULD
be labeled with an
IRI
Every
node
is an
IRI
, a
blank node
, a
JSON-LD value
or a
list
node
having an outgoing edge
MUST
be an
IRI
or a
blank node
graph
MUST NOT
contain unconnected
nodes
i.e., nodes which are not connected by an
edge
to any other
node
An
IRI
(Internationalized Resource Identifier) is a string that conforms to the syntax
defined in [
RFC3987
].
IRIs
used within a
graph
SHOULD
return a Linked Data document describing
the resource denoted by that
IRI
when being dereferenced.
blank node
is a
node
which is neither an
IRI
nor a
JSON-LD value
, nor a
list
. A blank node
MAY
be identified
using a
blank node identifier
blank node identifier
is a string that can be used as an identifier for a
blank node
within
the scope of a
JSON-LD document
. Blank node identifiers begin with
_:
JSON-LD value
is a
typed value
, a
string
(which is interpreted
as
typed value
with type
xsd:string
), a
number
numbers
with a non-zero fractional part, i.e., the result of a modulo‑1 operation,
are interpreted as
typed values
with type
xsd:double
, all other
numbers
are interpreted as
typed values
with type
xsd:integer
),
true
or
false
(which are interpreted as
typed values
with type
xsd:boolean
),
or a
language-tagged string
typed value
consists of a value, which is a string, and a type, which is an
IRI
language-tagged string
consists of a string and a non-empty language tag as defined by [
BCP47
].
The language tag
MUST
be well-formed according to section
2.2.9 Classes of Conformance
of [
BCP47
].
list
is a sequence of zero or more
IRIs
blank nodes
, and
JSON-LD values
Lists
are interpreted as
RDF list structures
RDF11-MT
].
Feature at Risk 3
: Allow blank nodes to be used as properties
Note: This feature is
"at risk"
and may
be removed from this specification based on feedback. Please send feedback to
public-rdf-comments@w3.org
For the current status see
features "at risk" in JSON-LD 1.0
RDF does not currently allow a
blank node
to be
used as a
property
, while JSON-LD
does. JSON-LD to RDF deserializers can work around this restriction, when interpreting
JSON-LD as RDF, by transforming such
blank nodes
to
IRIs
, by minting new "Skolem IRIs" as per
Replacing Blank Nodes with IRIs
of [
RDF11-CONCEPTS
]. Based on feedback from implementors, the
Working Group may decide to disallow blank node properties in JSON-LD.
If this change would affect you, be sure to send in a comment.
JSON-LD documents
MAY
contain data
that cannot be represented by the
data model
defined above. Unless otherwise specified, such data is ignored when a
JSON-LD document
is being processed. One result of this rule
is that properties which are not mapped to an
IRI
blank node
, or
keyword
will be ignored.
Figure 1: An illustration of the data model.
8.
JSON-LD Grammar
This appendix restates the syntactic conventions described in the
previous sections more formally.
JSON-LD document
MUST
be a valid JSON document as described
in [
RFC4627
].
JSON-LD document
MUST
be a single
node object
or an
array
whose elements are each
node objects
at the top level.
In contrast to JSON, in JSON-LD the keys in
objects
MUST
be unique.
Note
JSON-LD allows
keywords
to be aliased
(see
section 6.15 Aliasing Keywords
for details). Whenever a
keyword
is
discussed in this grammar, the statements also apply to an alias for
that
keyword
. For example, if the
active context
defines the
term
id
as an alias for
@id
that alias may be legitimately used as a substitution for
@id
Note that
keyword
aliases are not expanded during context
processing.
8.1
term
is a short-hand
string
that expands
to an
IRI
or a
blank node identifier
term
MUST NOT
equal any of the JSON-LD
keywords
To avoid forward-compatibility issues, a
term
SHOULD NOT
start
with an
character as future versions of JSON-LD may introduce
additional
keywords
. Furthermore, the term
MUST NOT
be an empty
string
""
) as not all programming languages
are able to handle empty JSON keys.
See
section 5.1 The Context
and
section 5.2 IRIs
for further discussion
on mapping
to
IRIs
8.2
Node Objects
node object
represents zero or more properties of a
node
in the
graph
serialized by the
JSON-LD document
. A
JSON object
is a
node object
if it exists outside of a JSON-LD
context
and:
it does not contain the
@value
@list
or
@set
keywords, and
it is not the top-most
JSON object
in the JSON-LD document
consisting of no other members than
@graph
and
@context
The
properties
of a
node
in
graph
may be spread among different
node objects
within a document. When
that happens, the keys of the different
node objects
need to be merged to create the
properties of the resulting
node
node object
MUST
be a
JSON object
. All keys
which are not
IRIs
compact IRIs
valid in the
active context
, or one of the following
keywords
MUST
be ignored when processed:
@context
@id
@graph
@type
@reverse
, or
@index
If the
node object
contains the
@context
key, its value
MUST
be
null
, an
absolute
IRI
relative
IRI
, a
context definition
, or
an
array
composed of any of these.
If the
node object
contains the
@id
key,
its value
MUST
be an
absolute
IRI
, a
relative
IRI
or a
compact
IRI
(including
blank node identifiers
).
See
section 5.3 Node Identifiers
section 6.3 Compact IRIs
, and
section 6.14 Identifying Blank Nodes
for further discussion on
@id
values.
If the
node object
contains the
@graph
key, its value
MUST
be
node object
or
an
array
of zero or more
node objects
If the
node object
contains an
@id
keyword,
its value is used as the label of a named graph.
See
section 6.13 Named Graphs
for further discussion on
@graph
values. As a special case, if a
JSON object
contains no keys other than
@graph
and
@context
, and the
JSON object
is the root of the JSON-LD document, the
JSON object
is not treated as a
node object
; this
is used as a way of defining
node
definitions
that may not form a connected graph. This allows a
context
to be defined which is shared by all of the constituent
node objects
If the
node object
contains the
@type
key, its value
MUST
be either an
absolute
IRI
, a
relative
IRI
, a
compact
IRI
(including
blank node identifiers
),
term
defined in the
active context
expanding into an
absolute
IRI
, or
an
array
of any of these.
See
section 5.4 Specifying the Type
for further discussion on
@type
values.
If the
node object
contains the
@reverse
key,
its value
MUST
be a
JSON object
containing members representing reverse
properties. Each value of such a reverse property
MUST
be an
absolute
IRI
relative
IRI
, a
compact
IRI
, a
blank node identifier
node object
or an
array
containing a combination of these.
If the
node object
contains the
@index
key,
its value
MUST
be a
string
. See
section 6.16 Data Indexing
for further discussion
on
@index
values.
Keys in a
node object
that are not
keywords
MAY
expand to an
absolute
IRI
using the
active context
. The values associated with keys that expand
to an
absolute
IRI
MUST
be one of the following:
string
number
true
false
null
node object
value object
list object
set object
an
array
of zero or more of the possibilities above,
language map
, or
an
index map
8.3
Value Objects
value object
is used to explicitly associate a type or a
language with a value to create a
typed value
or a
language-tagged
string
value object
MUST
be a
JSON object
containing the
@value
key. It
MAY
also contain a
@type
@language
, an
@index
, or an
@context
key but
MUST NOT
contain
both a
@type
and a
@language
key at the same time.
value object
MUST NOT
contain any other keys that expand to an
absolute
IRI
or
keyword
The value associated with the
@value
key
MUST
be either a
string
, a
number
true
false
or
null
The value associated with the
@type
key
MUST
be a
term
, a
compact
IRI
an
absolute
IRI
, a
relative
IRI
, or
null
The value associated with the
@language
key
MUST
have the
lexical form described in [
BCP47
], or be
null
The value associated with the
@index
key
MUST
be a
string
See
section 6.4 Typed Values
and
section 6.9 String Internationalization
for more information on
value objects
8.4
Lists and Sets
list
represents an
ordered
set of values. A set
represents an
unordered
set of values. Unless otherwise specified,
arrays
are unordered in JSON-LD. As such, the
@set
keyword, when used in the body of a JSON-LD document,
represents just syntactic sugar which is optimized away when processing the document.
However, it is very helpful when used within the context of a document. Values
of terms associated with a
@set
or
@list
container
will always be represented in the form of an
array
when a document
is processed—even if there is just a single value that would otherwise be optimized to
a non-array form in
compact document form
This simplifies post-processing of the data as the data is always in a
deterministic form.
list object
MUST
be a
JSON object
that contains no
keys that expand to an
absolute
IRI
or
keyword
other
than
@list
@context
, and
@index
set object
MUST
be a
JSON object
that contains no
keys that expand to an
absolute
IRI
or
keyword
other
than
@list
@context
, and
@index
Please note that the
@index
key will be ignored when being processed.
In both cases, the value associated with the keys
@list
and
@set
MUST
be one of the following types:
string
number
true
false
null
node object
value object
, or
an
array
of zero or more of the above possibilities
See
section 6.11 Sets and Lists
for further discussion on sets and lists.
8.5
Language Maps
language map
is used to associate a language with a value in a
way that allows easy programmatic access. A
language map
may be
used as a term value within a
node object
if the term is defined
with
@container
set to
@language
. The keys of a
language map
MUST
be
strings
representing
BCP47
] language codes with and the values
MUST
be any of the following types:
null
string
, or
an
array
of zero or more of the above possibilities
See
section 6.9 String Internationalization
for further discussion
on language maps.
8.6
Index Maps
An
index map
allows keys that have no semantic meaning,
but should be preserved regardless, to be used in JSON-LD documents.
An
index map
may
be used as a
term
value within a
node object
if the
term is defined with
@container
set to
@index
The values of the members of an
index map
MUST
be one
of the following types:
string
number
true
false
null
node object
value object
list object
set object
an
array
of zero or more of the above possibilities
See
section 6.16 Data Indexing
for further information on this topic.
8.7
Context Definitions
context definition
defines a
local context
in a
node object
context definition
MUST
be a
JSON object
whose
keys
MUST
either be
compact IRIs
absolute IRIs
or the
keywords
@language
@base
and
@vocab
If the
context definition
has a
@language
key,
its value
MUST
have the lexical form described in [
BCP47
] or be
null
If the
context definition
has a
@base
key,
its value
MUST
be an
absolute
IRI
, a
relative
IRI
or
null
If the
context definition
has a
@vocab
key,
its value
MUST
be a
absolute
IRI
, a
compact
IRI
blank node identifier
, a
term
, or
null
The value of keys that are not
keywords
MUST
be either an
absolute
IRI
, a
compact
IRI
, a
term
blank node identifier
, a
keyword
null
or an
expanded term definition
An
expanded term definition
is used to describe the mapping
between a
term
and its expanded identifier, as well as other
properties of the value associated with the
term
when it is
used as key in a
node object
An
expanded term definition
MUST
be a
JSON object
composed of zero or more keys from
@id
@reverse
@type
@language
or
@container
. An
expanded term definition
SHOULD NOT
contain any other keys.
If an
expanded term definition
has an
@reverse
member,
it
MUST NOT
have an
@id
member at the same time. If an
@container
member exists, its value
MUST
be
null
@set
, or
@index
If the term being defined is not a
compact
IRI
or
absolute
IRI
and the
active context
does not have an
@vocab
mapping, the
expanded term definition
MUST
include the
@id
key.
If the
expanded term definition
contains the
@id
keyword
, its value
MUST
be
null
, an
absolute
IRI
blank node identifier
, a
compact
IRI
, a
term
or a
keyword
If the
expanded term definition
contains the
@type
keyword
, its value
MUST
be an
absolute
IRI
, a
compact
IRI
, a
term
null
, or the one of the
keywords
@id
or
@vocab
If the
expanded term definition
contains the
@language
keyword
its value
MUST
have the lexical form described in [
BCP47
] or be
null
If the
expanded term definition
contains the
@container
keyword
, its value
MUST
be either
@list
@set
@language
@index
, or be
null
. If the value
is
@language
, when the
term
is used outside of the
@context
, the associated value
MUST
be a
language map
If the value is
@index
, when the
term
is used outside of
the
@context
, the associated value
MUST
be an
index map
MUST NOT
be used in a circular manner. That is,
the definition of a term cannot depend on the definition of another term if that other
term also depends on the first term.
See
section 5.1 The Context
for further discussion on contexts.
9.
Relationship to RDF
JSON-LD is a
concrete RDF syntax
as described in [
RDF11-CONCEPTS
]. Hence, a JSON-LD document is both an
RDF document
and
a JSON document and correspondingly represents an
instance of an RDF data model. However, JSON-LD also extends the RDF data
model to optionally allow JSON-LD to serialize
Generalized RDF Datasets
The JSON-LD extensions to the RDF data model are:
In JSON-LD
properties
can be
IRIs
or
blank nodes
whereas in RDF properties (predicates) have to be
IRIs
. This
means that JSON-LD serializes
generalized RDF Datasets
In JSON-LD
lists
are part of the data model
whereas in RDF they are part of a vocabulary, namely [
RDF-SCHEMA
].
RDF values are either typed
literals
typed values
) or
language-tagged strings
language-tagged strings
) whereas
JSON-LD also supports JSON's native data types, i.e.,
number
strings
, and the boolean values
true
and
false
. The JSON-LD Processing Algorithms and API specification [
JSON-LD-API
defines the
conversion rules
between JSON's native data types and RDF's counterparts to allow round-tripping.
Summarized, these differences mean that JSON-LD is capable of serializing any RDF
graph or dataset and most, but not all, JSON-LD documents can be directly
interpreted as RDF as described in RDF 1.1 Concepts [
RDF11-CONCEPTS
].
For authors and developers working with
blank nodes
as
properties
when deserializing to RDF,
three potential approaches are suggested:
If the author is not yet ready to commit to a stable
IRI
, the
property should be mapped to an
IRI
that is documented as unstable.
If the developer wishes to use
blank nodes
as
properties
and also wishes to interpret the
data as a
generalized RDF Dataset
there is an option,
produce generalized RDF
, in the
Deserialize JSON-LD to RDF algorithm [
JSON-LD-API
] to do so. Note that a
generalized RDF Dataset
is an extension of RDF; it does not conform to the RDF standard.
If the author or developer wishes to use
blank nodes
as
properties
and wishes to interpret the data
as a standard (non-generalized)
RDF Dataset
it is possible to losslessly interpret JSON-LD as RDF by transforming
blank nodes
used as
properties
to
IRIs
by minting new "Skolem IRIs" as per
Replacing Blank Nodes with IRIs
of [
RDF11-CONCEPTS
].
The normative algorithms for interpreting JSON-LD as RDF and serializing
RDF as JSON-LD are specified in the JSON-LD Processing Algorithms and API
specification [
JSON-LD-API
].
Even though JSON-LD serializes
generalized RDF Datasets
, it can
also be used as a
RDF graph source
In that case, a consumer
MUST
only use the default graph and ignore all named graphs.
This allows servers to expose data in languages such as Turtle and JSON-LD
using content negotiation.
Note
Publishers supporting both dataset and graph syntaxes have to ensure that
the primary data is stored in the default graph to enable consumers that do not support
datasets to process the information.
9.1
Serializing/Deserializing RDF
This section is non-normative.
The process of serializing RDF as JSON-LD and deserializing JSON-LD to RDF
depends on executing the algorithms defined in
RDF Serialization-Deserialization Algorithms
in the JSON-LD Processing Algorithms and API specification [
JSON-LD-API
].
It is beyond the scope of this document to detail these algorithms any further,
but a summary of the necessary operations is provided to illustrate the process.
The procedure to deserialize a JSON-LD document to RDF involves the
following steps:
Expand the JSON-LD document, removing any context; this ensures
that properties, types, and values are given their full representation
as
IRIs
and expanded values. Expansion
is discussed further in
section 6.17 Expanded Document Form
Flatten the document, which turns the document into an array of
node objects
. Flattening is discussed
further in
section 6.19 Flattened Document Form
Turn each
node object
into a series of
RDF triples
For example, consider the following JSON-LD document in compact form:
Example 63
: Sample JSON-LD document
"@context": {
"name": "http://xmlns.com/foaf/0.1/name",
"knows": "http://xmlns.com/foaf/0.1/knows"
},
"@id": "http://me.markus-lanthaler.com/",
"name": "Markus Lanthaler",
"knows": [
"@id": "http://manu.sporny.org/about#manu",
"name": "Manu Sporny"
},
"name": "Dave Longley"
Running the JSON-LD Expansion and Flattening algorithms against the
JSON-LD input document in the example above would result in the
following output:
Example 64
: Flattened and expanded form for the previous example
"@id": "_:b0",
"http://xmlns.com/foaf/0.1/name": "Dave Longley"
},
"@id": "http://manu.sporny.org/about#manu",
"http://xmlns.com/foaf/0.1/name": "Manu Sporny"
},
"@id": "http://me.markus-lanthaler.com/",
"http://xmlns.com/foaf/0.1/name": "Markus Lanthaler",
"http://xmlns.com/foaf/0.1/knows": [
{ "@id": "http://manu.sporny.org/about#manu" },
{ "@id": "_:b0" }
Deserializing this to RDF now is a straightforward process of turning
each
node object
into one or more RDF triples. This can be
expressed in Turtle as follows:
Example 65
: Turtle representation of expanded/flattened document
_:b0 "Dave Longley" .

"Manu Sporny" .

"Markus Lanthaler" ;
, _:b0 .
The process of serializing RDF as JSON-LD can be thought of as the
inverse of this last step, creating an expanded JSON-LD document closely
matching the triples from RDF, using a single
node object
for all triples having a common subject, and a single
property
for those triples also having a common predicate.
A.
Relationship to Other Linked Data Formats
This section is non-normative.
The JSON-LD examples below demonstrate how JSON-LD can be used to
express semantic data marked up in other linked data formats such as Turtle,
RDFa, Microformats, and Microdata. These sections are merely provided as
evidence that JSON-LD is very flexible in what it can express across different
Linked Data approaches.
A.1
Turtle
This section is non-normative.
The following are examples of transforming RDF expressed in Turtle [
TURTLE
into JSON-LD.
Prefix definitions
This section is non-normative.
The JSON-LD context has direct equivalents for the Turtle
@prefix
declaration:
Example 66
: A set of statements serialized in Turtle
@prefix foaf: .

a foaf:Person;
foaf:name "Manu Sporny";
foaf:homepage .
Example 67
: The same set of statements serialized in JSON-LD
"@context":
"foaf": "http://xmlns.com/foaf/0.1/"
},
"@id": "http://manu.sporny.org/about#manu",
"@type": "foaf:Person",
"foaf:name": "Manu Sporny",
"foaf:homepage": { "@id": "http://manu.sporny.org/" }
Embedding
Both Turtle and JSON-LD allow embedding, although Turtle only allows embedding of
blank nodes
Example 68
: Embedding in Turtle
@prefix foaf: .

a foaf:Person;
foaf:name "Manu Sporny";
foaf:knows [ a foaf:Person; foaf:name "Gregg Kellogg" ] .
Example 69
: Same embedding example in JSON-LD
"@context":
"foaf": "http://xmlns.com/foaf/0.1/"
},
"@id": "http://manu.sporny.org/about#manu",
"@type": "foaf:Person",
"foaf:name": "Manu Sporny",
"foaf:knows":
"@type": "foaf:Person",
"foaf:name": "Gregg Kellogg"
Conversion of native data types
In JSON-LD numbers and boolean values are native data types. While Turtle
has a shorthand syntax to express such values, RDF's abstract syntax requires
that numbers and boolean values are represented as typed literals. Thus,
to allow full round-tripping, the JSON-LD Processing Algorithms and API specification [
JSON-LD-API
defines conversion rules between JSON-LD's native data types and RDF's
counterparts.
Numbers
without fractions are
converted to
xsd:integer
-typed literals, numbers with fractions
to
xsd:double
-typed literals and the two boolean values
true
and
false
to a
xsd:boolean
-typed
literal. All typed literals are in canonical lexical form.
Example 70
: JSON-LD using native data types for numbers and boolean values
"@context":
"ex": "http://example.com/vocab#"
},
"@id": "http://example.com/",
"ex:numbers": [ 14, 2.78 ],
"ex:booleans": [ true, false ]
Example 71
: Same example in Turtle using typed literals
@prefix ex: .
@prefix xsd: .

ex:numbers "14"^^xsd:integer, "2.78E0"^^xsd:double ;
ex:booleans "true"^^xsd:boolean, "false"^^xsd:boolean .
Lists
Both JSON-LD and Turtle can represent sequential lists of values.
Example 72
: A list of values in Turtle
@prefix foaf: .

a foaf:Person;
foaf:name "Joe Bob";
foaf:nick ( "joe" "bob" "jaybee" ) .
Example 73
: Same example with a list of values in JSON-LD
"@context":
"foaf": "http://xmlns.com/foaf/0.1/"
},
"@id": "http://example.org/people#joebob",
"@type": "foaf:Person",
"foaf:name": "Joe Bob",
"foaf:nick":
"@list": [ "joe", "bob", "jaybee" ]
A.2
RDFa
This section is non-normative.
The following example describes three people with their respective names and
homepages in RDFa [
RDFA-CORE
].
Example 74
: RDFa fragment that describes three people
prefix="foaf: http://xmlns.com/foaf/0.1/"

typeof="foaf:Person"
rel="foaf:homepage" href="http://example.com/bob/" property="foaf:name"
>Bob

typeof="foaf:Person"
rel="foaf:homepage" href="http://example.com/eve/" property="foaf:name"
>Eve

typeof="foaf:Person"
rel="foaf:homepage" href="http://example.com/manu/" property="foaf:name"
>Manu

An example JSON-LD implementation using a single
context
is
described below.
Example 75
: Same description in JSON-LD (context shared among node objects)
"@context":
"foaf": "http://xmlns.com/foaf/0.1/"
},
"@graph":
"@type": "foaf:Person",
"foaf:homepage": "http://example.com/bob/",
"foaf:name": "Bob"
},
"@type": "foaf:Person",
"foaf:homepage": "http://example.com/eve/",
"foaf:name": "Eve"
},
"@type": "foaf:Person",
"foaf:homepage": "http://example.com/manu/",
"foaf:name": "Manu"
A.3
Microformats
This section is non-normative.
The following example uses a simple Microformats hCard example to express
how Microformats [
MICROFORMATS
] are represented in JSON-LD.
Example 76
: HTML fragment with a simple Microformats hCard

Tantek Çelik

The representation of the hCard expresses the Microformat terms in the
context
and uses them directly for the
url
and
fn
properties. Also note that the Microformat to JSON-LD processor has
generated the proper URL type for
Example 77
: Same hCard representation in JSON-LD
"@context":
"vcard": "http://microformats.org/profile/hcard#vcard",
"url":
"@id": "http://microformats.org/profile/hcard#url",
"@type": "@id"
},
"fn": "http://microformats.org/profile/hcard#fn"
},
"@type": "vcard",
"url": "http://tantek.com/",
"fn": "Tantek Çelik"
A.4
Microdata
This section is non-normative.
The HTML Microdata [
MICRODATA
] example below expresses book information as
a Microdata Work item.
Example 78
: HTML fragments that describes a book using microdata

Title: Just a Geek
By: Wil Wheaton
Format: itemscope
itemtype="http://purl.org/vocab/frbr/core#Expression"
itemid="http://purl.oreilly.com/products/9780596007683.BOOK">; itemscope
itemtype="http://purl.org/vocab/frbr/core#Expression"
itemid="http://purl.oreilly.com/products/9780596802189.EBOOK">

Ebook

Note that the JSON-LD representation of the Microdata information stays
true to the desires of the Microdata community to avoid contexts and
instead refer to items by their full
IRI
Example 79
: Same book description in JSON-LD (avoiding contexts)
"@id": "http://purl.oreilly.com/works/45U8QJGZSQKDH8N",
"@type": "http://purl.org/vocab/frbr/core#Work",
"http://purl.org/dc/terms/title": "Just a Geek",
"http://purl.org/dc/terms/creator": "Whil Wheaton",
"http://purl.org/vocab/frbr/core#realization":
"http://purl.oreilly.com/products/9780596007683.BOOK",
"http://purl.oreilly.com/products/9780596802189.EBOOK"
},
"@id": "http://purl.oreilly.com/products/9780596007683.BOOK",
"@type": "http://purl.org/vocab/frbr/core#Expression",
"http://purl.org/dc/terms/type": "http://purl.oreilly.com/product-types/BOOK"
},
"@id": "http://purl.oreilly.com/products/9780596802189.EBOOK",
"@type": "http://purl.org/vocab/frbr/core#Expression",
"http://purl.org/dc/terms/type": "http://purl.oreilly.com/product-types/EBOOK"
B.
IANA Considerations
This section has been submitted to the Internet Engineering Steering
Group (IESG) for review, approval, and registration with IANA.
application/ld+json
Type name:
application
Subtype name:
ld+json
Required parameters:
None
Optional parameters:
profile
A a non-empty list of space-separated URIs identifying specific
constraints or conventions that apply to a JSON-LD document according [
RFC6906
].
A profile does not change the semantics of the resource representation
when processed without profile knowledge, so that clients both with
and without knowledge of a profiled resource can safely use the same
representation. The
profile
parameter
MAY
be used by
clients to express their preferences in the content negotiation process.
If the profile parameter is given, a server
SHOULD
return a document that
honors the profiles in the list which are recognized by the server.
It is
RECOMMENDED
that profile URIs are dereferenceable and provide
useful documentation at that URI. For more information and background
please refer to [
RFC6906
].
This specification defines three values for the
profile
parameter.
To request or specify
expanded JSON-LD document form
the URI
SHOULD
be used.
To request or specify
compacted JSON-LD document form
the URI
SHOULD
be used.
To request or specify
flattened JSON-LD document form
the URI
SHOULD
be used.
Please note that, according [
HTTP11
], the value of the
profile
parameter has to be enclosed in quotes (
) because it contains
special characters and, if multiple profiles are combined, whitespace.
When processing the "profile" media type parameter, it is important to
note that its value contains one or more URIs and not IRIs. In some cases
it might therefore be necessary to convert between IRIs and URIs as specified in
section 3 Relationship between IRIs and URIs
of [
RFC3987
].
Encoding considerations:
See RFC 6839, section 3.1.
Security considerations:
See [
RFC4627
Since JSON-LD is intended to be a pure data exchange format for
directed graphs, the serialization
SHOULD NOT
be passed through a
code execution mechanism such as JavaScript's
eval()
function to be parsed. An (invalid) document may contain code that,
when executed, could lead to unexpected side effects compromising
the security of a system.
When processing JSON-LD documents, links to remote contexts are
typically followed automatically, resulting in the transfer of files
without the explicit request of the user for each one. If remote
contexts are served by third parties, it may allow them to gather
usage patterns or similar information leading to privacy concerns.
Specific implementations, such as the API defined in the
JSON-LD Processing Algorithms and API specification [
JSON-LD-API
],
may provide fine-grained mechanisms to control this behavior.
JSON-LD contexts that are loaded from the Web over non-secure connections,
such as HTTP, run the risk of being altered by an attacker such that
they may modify the JSON-LD
active context
in a way that
could compromise security. It is advised that any application that
depends on a remote context for mission critical purposes vet and
cache the remote context before allowing the system to use it.
Given that JSON-LD allows the substitution of long IRIs with short terms,
JSON-LD documents may expand considerably when processed and, in the worst case,
the resulting data might consume all of the recipient's resources. Applications
should treat any data with due skepticism.
Interoperability considerations:
Not Applicable
Published specification:
Applications that use this media type:
Any programming environment that requires the exchange of
directed graphs. Implementations of JSON-LD have been created for
JavaScript, Python, Ruby, PHP, and C++.
Additional information:
Magic number(s):
Not Applicable
File extension(s):
.jsonld
Macintosh file type code(s):
TEXT
Person & email address to contact for further information:
Manu Sporny
Intended usage:
Common
Restrictions on usage:
None
Author(s):
Manu Sporny, Dave Longley, Gregg Kellogg, Markus Lanthaler, Niklas Lindström
Change controller:
W3C
Fragment identifiers used with
application/ld+json
are treated as in RDF syntaxes, as per
RDF 1.1 Concepts and Abstract Syntax
RDF11-CONCEPTS
].
C.
Acknowledgements
This section is non-normative.
The authors would like to extend a deep appreciation and the most sincere
thanks to Mark Birbeck, who contributed foundational concepts
to JSON-LD via his work on RDFj. JSON-LD uses a number of core concepts
introduced in RDFj, such as the context as a mechanism to provide an
environment for interpreting JSON data. Mark had also been very involved in
the work on RDFa as well. RDFj built upon that work. JSON-LD exists
because of the work and ideas he started nearly a decade ago in 2004.
A large amount of thanks goes out to the JSON-LD Community Group
participants who worked through many of the technical issues on the mailing
list and the weekly telecons - of special mention are François Daoust,
Stéphane Corlosquet, Lin Clark, and Zdenko 'Denny' Vrandečić.
The work of David I. Lehn and Mike Johnson are appreciated for
reviewing, and performing several early implementations
of the specification. Thanks also to Ian Davis for this work on RDF/JSON.
Thanks to the following individuals, in order of their first name, for
their input on the specification: Adrian Walker, Alexandre Passant,
Andy Seaborne, Ben Adida, Blaine Cook, Bradley Allen, Brian Peterson,
Bryan Thompson, Conal Tuohy, Dan Brickley, Danny Ayers, Daniel Leja,
Dave Reynolds, David Booth, David I. Lehn, David Wood, Dean Landolt,
Ed Summers, elf Pavlik,
Eric Prud'hommeaux, Erik Wilde, Fabian Christ, Jon A. Frost, Gavin Carothers,
Glenn McDonald, Guus Schreiber, Henri Bergius, Jose María Alvarez Rodríguez,
Ivan Herman, Jack Moffitt, Josh Mandel, KANZAKI Masahide, Kingsley Idehen,
Kuno Woudt, Larry Garfield, Mark Baker, Mark MacGillivray, Marko Rodriguez,
Marios Meimaris,
Melvin Carvalho, Nathan Rixham, Olivier Grisel, Paolo Ciccarese, Pat Hayes,
Patrick Logan, Paul Kuykendall, Pelle Braendgaard,
Peter Patel-Schneider, Peter Williams, Pierre-Antoine Champin,
Richard Cyganiak, Roy T. Fielding, Sandro Hawke, Srecko Joksimovic,
Stephane Fellah, Steve Harris, Ted Thibodeau Jr., Thomas Steiner, Tim Bray,
Tom Morris, Tristan King, Sergio Fernández, Werner Wilms, and William Waites.
D.
References
D.1
Normative references
[BCP47]
A. Phillips; M. Davis.
Tags for Identifying Languages
. September 2009. IETF Best Current Practice. URL:
[RDF11-CONCEPTS]
Richard Cyganiak, David Wood, Editors.
RDF 1.1 Concepts and Abstract Syntax.
23 July 2013. W3C Last Call Working Draft (work in progress). URL:
. The latest edition is available at
[RFC2119]
S. Bradner.
Key words for use in RFCs to Indicate Requirement Levels.
March 1997. Internet RFC 2119. URL:
[RFC3987]
M. Dürst; M. Suignard.
Internationalized Resource Identifiers (IRIs)
. January 2005. RFC. URL:
[RFC4627]
D. Crockford.
The application/json Media Type for JavaScript Object Notation (JSON) (RFC 4627)
. July 2006. RFC. URL:
[RFC5988]
M. Nottingham.
Web Linking
October 2010. Internet RFC 5988. URL:
D.2
Informative references
[HTTP11]
R. Fielding et al.
Hypertext Transfer Protocol - HTTP/1.1
. June 1999. RFC. URL:
[JSON-LD-API]
Markus Lanthaler, Gregg Kellogg, Manu Sporny, Editors.
JSON-LD 1.0 Processing Algorithms and API
W3C Candidate Recommendation (work in progress). URL:
. The latest edition is available at
[JSON-LD-TESTS]
JSON-LD 1.0 Test Suite
. W3C Test Suite (work in progress). URL:
[LINKED-DATA]
Tim Berners-Lee.
Linked Data
. Personal View, imperfect but published. URL:
[MICRODATA]
Ian Hickson, Editor.
HTML Microdata
25 October 2012. W3C Working Draft (work in progress). URL:
. The latest edition is available at
[MICROFORMATS]
Microformats
. URL:
[RDF-SCHEMA]
Dan Brickley; Ramanathan Guha.
RDF Vocabulary Description Language 1.0: RDF Schema
. 10 February 2004. W3C Recommendation. URL:
[RDF11-MT]
Patrick J. Hayes, Peter F. Patel-Schneider, Editors.
RDF 1.1 Semantics.
23 July 2013. W3C Last Call Working Draft (work in progress). URL:
. The latest edition is available at
[RDFA-CORE]
Ben Adida; Mark Birbeck; Shane McCarron; Ivan Herman et al.
RDFa Core 1.1 - Second Edition
. 22 August 2013. W3C Recommendation. URL:
[RFC3986]
T. Berners-Lee; R. Fielding; L. Masinter.
Uniform Resource Identifier (URI): Generic Syntax (RFC 3986)
. January 2005. RFC. URL:
[RFC6839]
Tony Hansen, Alexey Melnikov.
Additional Media Type Structured Syntax Suffixes
January 2013. Internet RFC 6839. URL:
[RFC6906]
Erik Wilde.
The 'profile' Link Relation Type
March 2013. Internet RFC 6906. URL:
[TURTLE]
Eric Prud'hommeaux, Gavin Carothers, Editors.
Turtle: Terse RDF Triple Language.
19 February 2013. W3C Candidate Recommendation (work in progress). URL:
. The latest edition is available at

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