ISO 16684-3:2021

Graphic technology — Extensible metadata platform (XMP) specification — Part 3: JSON-LD serialization of XMP

This document defines how the XMP data model can be serialized to JSON-LD.

Titre manque — Partie 3: Titre manque

General Information

• Status: Published
• Publication Date: 17-Aug-2021
• ICS: 35.240.30 - IT applications in information, documentation and publishing
• ICS: 37.100.99 - Other standards related to graphic technology
• Technical Committee: ISO/TC 171/SC 2 - Document file formats, EDMS systems and authenticity of information
• Drafting Committee: ISO/TC 171/SC 2 - Document file formats, EDMS systems and authenticity of information
• Current Stage: 6060 - International Standard published
• Start Date: 18-Aug-2021
• Due Date: 28-Nov-2023
• Completion Date: 18-Aug-2021

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 16684-3
First edition
2021-08
Graphic technology — Extensible
metadata platform (XMP)
specification —
Part 3:
JSON-LD serialization of XMP
Reference number
ISO 16684-3:2021(E)
©
ISO 2021

---------------------- Page: 1 ----------------------
ISO 16684-3:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 16684-3:2021(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3  Terms and definitions . 1
4 XMP – JSON-LD serialization. 1
4.1 Namespace prefix serialization . 1
4.2 Property Names in JSON-LD . 2
4.3 rdf:about serialization in JSON-LD as @id . 2
4.4 Use of @type JSON-LD keyword. 3
4.5 XMP property forms serialization in JSON-LD . 5
4.5.1 General. 5
4.5.2 Simple valued XMP Properties. 5
4.5.3 Array valued XMP properties . 6
4.5.4 Structure valued XMP properties . 8
4.5.5 Qualifiers . 9
4.6 Media type.13
Bibliography .14
© ISO 2021 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 16684-3:2021(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 171, Document management applications,
Subcommittee SC 2, Document file formats, EDMS systems and authenticity of information.
A list of all parts in the ISO 16684 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 16684-3:2021(E)

Introduction
The extensible metadata platform (XMP) was introduced by Adobe Systems Incorporated in 2001 and
has since established itself as a critical technology for improving business efficiency in many industries.
The current serialization of XMP model is available in RDF/XML format as described in ISO 16684-1.
This document provides a complete specification about how XMP can be serialized to JSON-LD.
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. It is also designed to be usable as RDF.
JSON-LD can distinguish between values which are simple strings and internationalized resource
identifiers (IRI). JSON itself has no built-in support for hyperlinks. Types of values can be indicated by
an IRI in JSON-LD. But this cannot be done naturally in JSON. It provides the ability to annotate strings
with their language.
Users of this document are cautioned that they are expected to be familiar with the documents listed as
1)
normative references and the terms used within those documents.
1) The PDF Association maintains an ongoing series of application notes for guiding developers and users of this
document. It also retains copies of the specific non-ISO normative references of this document which are publicly
available electronic documents.
© ISO 2021 – All rights reserved v

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 16684-3:2021(E)
Graphic technology — Extensible metadata platform (XMP)
specification —
Part 3:
JSON-LD serialization of XMP
1 Scope
This document defines how the XMP data model can be serialized to JSON-LD.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
JSON-LD 1.1, A JSON-based Serialization for Linked Data, W3C Recommendation, 16 July 2020, https://
www .w3 .org/ TR/ json -ld11
BCP-47, Tags for Identifying Languages. A. Phillips; M. Davis. IETF. September 2009. IETF Best Current
Practice. https:// tools .ietf .org/ html/ bcp47
3  Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 XMP – JSON-LD serialization
4.1  Namespace prefix serialization
Many of the terms used in this document come from JSON-LD 1.1.
According to ISO 16684-1, all names in XMP are XML expanded names, consisting of a namespace
uniform resource identifier (URI) and a local name. The shortcut term of the namespace URI is defined
inside the @context key in a JSON-LD document. All JSON-LD serializations of XMP shall contain a @
context key.
EXAMPLE 1 XMP serialized as RDF/XML and its corresponding serialized JSON-LD with namespace prefixes.
Serialized XMP Packet in RDF/XML
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:xmp="http://ns.adobe.com/xap/1.0/"
  xmlns:tiff="http://ns.adobe.com/tiff/1.0/">
  
      4
© ISO 2021 – All rights reserved 1

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ISO 16684-3:2021(E)

      1
  


Serialized XMP Packet in JSON-LD
{
  "@context": {
    "xmp": "http://ns.adobe.com/xap/1.0/",
    "tiff": "http://ns.adobe.com/tiff/1.0/"
  },
  "xmp:Rating": "4",
  "tiff:Orientation":"1",
  "@id": ""
}

Contexts can either be directly embedded into the document or be referenced. It is also possible to have
more than one context at different points in a document. The set of contexts defined within a specific
JSON object are referred to as local contexts.
NOTE The value of the @context key can either be a simple string (mapping the term to an IRI) or a JSON
object.
If all the contexts in EXAMPLE 1 were combined into a single file that could be retrieved at the @
context link shown in EXAMPLE 2 below, it can be referenced in the JSON-LD by adding a single line thus
allowing the JSON-LD document to be expressed much more concisely.
EXAMPLE 2 Use of externally referenced @context.
{
  "@context": "http://www.example.com/contexts/context1.jsonld",
  "xmp:Rating": 4,
  "tiff:Orientation": 1,
  "@id": ""
}

4.2 Property Names in JSON-LD
Property names are represented as keys in JSON-LD document. These keys shall be of the form compact
internationalized resource identifier (IRI). Compact IRI in JSON-LD is in the form of prefix:s uffix where
prefix refers to the namespace term defined in the context and suffix is local name in that namespace.
4.3 rdf: about serialization in JSON-LD as @id
ISO 16684-1:2019, 6.1 specifies that an XMP packet may contain a URI, called the AboutURI, that
identifies the resource that the packet describes. Additionally, ISO 16684-1:2019, 7.4 adds that if the
XMP data model has an AboutURI, that same URI shall be the value of an rdf: about attribute in each
top-level rdf: Description element. Otherwise, the rdf: about attributes for all top level rdf: Description
elements shall be present with an empty value. The rdf: about attribute shall not be used in more deeply
nested rdf: Description elements.
EXAMPLE Serialized XMP and its corresponding serialized JSON-LD with AboutURI.
Serialized XMP Packet in RDF/XML
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:xmp="http://ns.adobe.com/xap/1.0/">
  
    4
  

2 © ISO 2021 – All rights reserved

---------------------- Page: 7 ----------------------
ISO 16684-3:2021(E)


Serialized XMP Packet in JSON-LD
{
  "@context": {
    "xmp": "http://ns.adobe.com/xap/1.0/"
  },
  "@id": "http://www.example.com/abouturiEg/",
  "xmp:Rating": 4
}

NOTE It is possible for an XMP packet to not contain an AboutURI and not have a physical association with
the resource. Instead, there can be an external means of association.
If there is no AboutURI present (this can occur as XMP tolerates missing rdf: about attribute for
compatibility with very early XMP), then an empty @id shall be included in the root document.
4.4 Use of @type JSON-LD keyword
JSON-LD has @type keyword that can be used to specify node type and value type. A node type specifies
the type of thing that is being described. A value type specifies the data type of a particular value, such
as an integer, a floating-point number or a date.
In the RDF/XML serialization, the value type is expressed by rdf: datatype. However, this attribute is
not allowed in the JSON-LD serialization. The JSON-LD serialization allows for the use of rdf: node that
corresponds to node type (ISO 16684-1:2019, 7.9.2.5). In addition, the rdf: type property can be used
(but not a typed node, see ISO 16684-1:2019, 7.9.2.5).
EXAMPLE 1 Below is an example of rdf: type and its corresponding serialization in JSON-LD.
Serialized XMP Packet in RDF/XML:
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:xe="http://ns.adobe.com/xmp-example/"
  xmlns:xmp="http://ns.adobe.com/xap/1.0/">
  
    
    3
  


Serialized XMP Packet in JSON-LD
{
  "@context": {
    "xmp": "http://ns.adobe.com/xap/1.0/",
    "xe": "http://ns.adobe.com/xmp-example/"
  },
  "@id": "",
  "@type": "http://ns.adobe.com/xmp-example/myType",
  "xmp:Rating": 3
}

In RDF/XML serialization of XMP, the use of an inner typed node in XMP attaches an rdf: type qualifier to
the containing element. The value of the rdf: type qualifier is a URI consisting of the typed node element’s
namespace URI concatenated with the local name. In the JSON-LD serialization, the equivalent of rdf:
type is the @type keyword.
EXAMPLE 2 Inner typed node interpretation in XMP RDF/XML serialization.
© ISO 2021 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO 16684-3:2021(E)

   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:xe="http://ns.adobe.com/xmp-example/">
   
      
       
                 rdf:resource="http://ns.adobe.com/xmp-example/myType"/>
        
           value
        
       
     
   


Corresponding JSON-LD serialization
{
  "@context": {
    "xe": "http://ns.adobe.com/xmp-example/",
    "rdf":"http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  },
  "xe:Prop2": {
    "@type": "http://ns.adobe.com/xmp-example/myType",
    "rdf:value": {
      "xe:Field": "value"
    }
  }
}

Instead of @type, it is also acceptable to use rdf: type for consistency with the XML serialization.
EXAMPLE 3 Explicit rdf: type field in an XMP structure.
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:xe="http://ns.adobe.com/xmp-example/">
  
  
    
    
               rdf:resource="http://ns.adobe.com/xmp-example/myType"/>
      value
    
    
  


Corresponding JSON-LD serialization
{
 "@context": {
  "xe": "http://ns.adobe.com/xmp-example/",
  "rdf":"http://www.w3.org/1999/02/22-rdf-syntax-ns#"
 },
 "xe:Prop3": {
  "rdf:type": "http://ns.adobe.com/xmp-example/myType",
  "xe:Field": "value"
 }
}

4 © ISO 2021 – All rights reserved

---------------------- Page: 9 ----------------------
ISO 16684-3:2021(E)

4.5 XMP property forms serialization in JSON-LD
4.5.1 General
As per ISO 16684-1, values in the XMP data model have one of three forms:
— simple;
— structure;
— array.
The array form can be further classified as: unordered array, ordered array and alternative array. The
fields in structures and the items in arrays can have any value form. There is no fixed bound on the
complexity of XMP data modelling.
Subclauses 4.5.2 to 4.5.5 present the rules which shall be followed by conforming applications while
serializing any XMP to JSON-LD.
4.5.2 Simple valued XMP Properties
A simple value may be either a string of unicode text as defined in ISO/IEC 10646, a number, or one of
the three literal names defined in RFC 8259.
Any string value may be empty. A non-empty string value may be a URI, which when used as the value
of the @id key shall be interpreted as an IRI.
EXAMPLE 1 Serialization for non-URI simple value in RDF/XML format and JSON-LD
...

INTERNATIONAL ISO
STANDARD 16684-3
First edition
Graphic technology — Extensible
metadata platform (XMP)
specification —
Part 3:
JSON-LD serialization of XMP
Partie 3: Plate-forme de métadonnées extensibles (XMP)
PROOF/ÉPREUVE
Reference number
ISO 16684-3:2021(E)
©
ISO 2021

---------------------- Page: 1 ----------------------
ISO 16684-3:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 16684-3:2021(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3  Terms and definitions . 1
4 XMP – JSON-LD serialization. 1
4.1 Namespace prefix serialization . 1
4.2 Property Names in JSON-LD . 2
4.3 rdf:about serialization in JSON-LD as @id . 2
4.4 Use of @type JSON-LD keyword. 3
4.5 XMP property forms serialization in JSON-LD . 5
4.5.1 General. 5
4.5.2 Simple valued XMP Properties. 5
4.5.3 Array valued XMP properties . 6
4.5.4 Structure valued XMP properties . 8
4.5.5 Qualifiers . 9
4.6 Media type.13
Bibliography .14
© ISO 2021 – All rights reserved PROOF/ÉPREUVE iii

---------------------- Page: 3 ----------------------
ISO 16684-3:2021(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 171, Document management applications,
Subcommittee SC 2, Document file formats, EDMS systems and authenticity of information.
A list of all parts in the ISO 16684 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv PROOF/ÉPREUVE © ISO 2021 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 16684-3:2021(E)

Introduction
The extensible metadata platform (XMP) was introduced by Adobe Systems Incorporated in 2001 and
has since established itself as a critical technology for improving business efficiency in many industries.
The current serialization of XMP model is available in RDF/XML format as described in ISO 16684-1.
This document provides a complete specification about how XMP can be serialized to JSON-LD.
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. It is also designed to be usable as RDF.
JSON-LD can distinguish between values which are simple strings and internationalized resource
identifiers (IRI). JSON itself has no built-in support for hyperlinks. Types of values can be indicated by
an IRI in JSON-LD. But this cannot be done naturally in JSON. It provides the ability to annotate strings
with their language.
Users of this document are cautioned that they are expected to be familiar with the documents listed as
1)
normative references and the terms used within those documents.
1) The PDF Association maintains an ongoing series of application notes for guiding developers and users of this
document. It also retains copies of the specific non-ISO normative references of this document which are publicly
available electronic documents.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE v

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 16684-3:2021(E)
Graphic technology — Extensible metadata platform (XMP)
specification —
Part 3:
JSON-LD serialization of XMP
1 Scope
This document defines how the XMP data model can be serialized to JSON-LD.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
JSON-LD 1.1, A JSON-based Serialization for Linked Data, W3C Recommendation, 16 July 2020, https://
www .w3 .org/ TR/ json -ld11
BCP-47, Tags for Identifying Languages. A. Phillips; M. Davis. IETF. September 2009. IETF Best Current
Practice. https:// tools .ietf .org/ html/ bcp47
3  Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 XMP – JSON-LD serialization
4.1  Namespace prefix serialization
Many of the terms used in this document come from JSON-LD 1.1.
According to ISO 16684-1, all names in XMP are XML expanded names, consisting of a namespace
uniform resource identifier (URI) and a local name. The shortcut term of the namespace URI is defined
inside the @context key in a JSON-LD document. All JSON-LD serializations of XMP shall contain a @
context key.
EXAMPLE 1 XMP serialized as RDF/XML and its corresponding serialized JSON-LD with namespace prefixes.
Serialized XMP Packet in RDF/XML
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:xmp="http://ns.adobe.com/xap/1.0/"
  xmlns:tiff="http://ns.adobe.com/tiff/1.0/">
  
      4
© ISO 2021 – All rights reserved PROOF/ÉPREUVE 1

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ISO 16684-3:2021(E)

      1
  


Serialized XMP Packet in JSON-LD
{
  "@context": {
    "xmp": "http://ns.adobe.com/xap/1.0/",
    "tiff": "http://ns.adobe.com/tiff/1.0/"
  },
  "xmp:Rating": "4",
  "tiff:Orientation":"1",
  "@id": ""
}

Contexts can either be directly embedded into the document or be referenced. It is also possible to have
more than one context at different points in a document. The set of contexts defined within a specific
JSON object are referred to as local contexts.
NOTE The value of the @context key can either be a simple string (mapping the term to an IRI) or a JSON
object.
If all the contexts in EXAMPLE 1 were combined into a single file that could be retrieved at the @
context link shown in EXAMPLE 2 below, it can be referenced in the JSON-LD by adding a single line thus
allowing the JSON-LD document to be expressed much more concisely.
EXAMPLE 2 Use of externally referenced @context.
{
  "@context": "http://www.example.com/contexts/context1.jsonld",
  "xmp:Rating": 4,
  "tiff:Orientation": 1,
  "@id": ""
}

4.2 Property Names in JSON-LD
Property names are represented as keys in JSON-LD document. These keys shall be of the form compact
internationalized resource identifier (IRI). Compact IRI in JSON-LD is in the form of prefix:s uffix where
prefix refers to the namespace term defined in the context and suffix is local name in that namespace.
4.3 rdf: about serialization in JSON-LD as @id
ISO 16684-1:2019, 6.1 specifies that an XMP packet may contain a URI, called the AboutURI, that
identifies the resource that the packet describes. Additionally, ISO 16684-1:2019, 7.4 adds that if the
XMP data model has an AboutURI, that same URI shall be the value of an r df : ab out attribute in each
top-level r df : D e s c r ipt ion element. Otherwise, the r df : ab out attributes for all top level rdf: Description
elements shall be present with an empty value. The r df : ab out attribute shall not be used in more deeply
nested r df : D e s c r ipt ion elements.
EXAMPLE Serialized XMP and its corresponding serialized JSON-LD with AboutURI.
Serialized XMP Packet in RDF/XML
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:xmp="http://ns.adobe.com/xap/1.0/">
  
    4
  

2 PROOF/ÉPREUVE © ISO 2021 – All rights reserved

---------------------- Page: 7 ----------------------
ISO 16684-3:2021(E)


Serialized XMP Packet in JSON-LD
{
  "@context": {
    "xmp": "http://ns.adobe.com/xap/1.0/"
  },
  "@id": "http://www.example.com/abouturiEg/",
  "xmp:Rating": 4
}

NOTE It is possible for an XMP packet to not contain an AboutURI and not have a physical association with
the resource. Instead, there can be an external means of association.
If there is no AboutURI present (this can occur as XMP tolerates missing r df : ab out attribute for
compatibility with very early XMP), then an empty @id shall be included in the root document.
4.4 Use of @type JSON-LD keyword
JSON-LD has @type keyword that can be used to specify node type and value type. A node type specifies
the type of thing that is being described. A value type specifies the data type of a particular value, such
as an integer, a floating-point number or a date.
In the RDF/XML serialization, the value type is expressed by rdf: datatype. However, this attribute is
not allowed in the JSON-LD serialization. The JSON-LD serialization allows for the use of r df : no de that
corresponds to node type (ISO 16684-1:2019, 7.9.2.5). In addition, the rdf: type property can be used
(but not a typed node, see ISO 16684-1:2019, 7.9.2.5).
EXAMPLE 1 Below is an example of rdf: type and its corresponding serialization in JSON-LD.
Serialized XMP Packet in RDF/XML:
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:xe="http://ns.adobe.com/xmp-example/"
  xmlns:xmp="http://ns.adobe.com/xap/1.0/">
  
    
    3
  


Serialized XMP Packet in JSON-LD
{
  "@context": {
    "xmp": "http://ns.adobe.com/xap/1.0/",
    "xe": "http://ns.adobe.com/xmp-example/"
  },
  "@id": "",
  "@type": "http://ns.adobe.com/xmp-example/myType",
  "xmp:Rating": 3
}

In RDF/XML serialization of XMP, the use of an inner typed node in XMP attaches an rdf: type qualifier to
the containing element. The value of the rdf: type qualifier is a URI consisting of the typed node element’s
namespace URI concatenated with the local name. In the JSON-LD serialization, the equivalent of rdf:
type is the @type keyword.
EXAMPLE 2 Inner typed node interpretation in XMP RDF/XML serialization.
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ISO 16684-3:2021(E)

   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:xe="http://ns.adobe.com/xmp-example/">
   
      
       
                 rdf:resource="http://ns.adobe.com/xmp-example/myType"/>
        
           value
        
       
     
   


Corresponding JSON-LD serialization
{
  "@context": {
    "xe": "http://ns.adobe.com/xmp-example/",
    "rdf":"http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  },
  "xe:Prop2": {
    "@type": "http://ns.adobe.com/xmp-example/myType",
    "rdf:value": {
      "xe:Field": "value"
    }
  }
}

Instead of @type, it is also acceptable to use rdf: type for consistency with the XML serialization.
EXAMPLE 3 Explicit rdf: type field in an XMP structure.
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:xe="http://ns.adobe.com/xmp-example/">
  
  
    
    
               rdf:resource="http://ns.adobe.com/xmp-example/myType"/>
      value
    
    
  


Corresponding JSON-LD serialization
{
 "@context": {
  "xe": "http://ns.adobe.com/xmp-example/",
  "rdf":"http://www.w3.org/1999/02/22-rdf-syntax-ns#"
 },
 "xe:Prop3": {
  "rdf:type": "http://ns.adobe.com/xmp-example/myType",
  "xe:Field": "value"
 }
}

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ISO 16684-3:2021(E)

4.5 XMP property forms serialization in JSON-LD
4.5.1 General
As per ISO 16684-1, values in the XMP data model have one of three forms:
— simple;
— structure;
— array.
The array form can be further classified as: unordered array, ordered array and alternative array. The
fields in structures and the items in arrays can have any value form. There is no fixed bound on the
complexity of XMP data modelling.
Subclauses 4.5.2 to 4.5.5 present the rules which shall be followed by conforming applications while
serializing any XMP to JSON-LD.
4.5.2 Simple valued XMP Properties
A simple value may be either a string of unicode text as defined in ISO/IEC 10646, a number, or one of
the three literal names defined in RFC 8259.
Any string value may be empty. A non-empty string value may be a URI, which when used as the value
of the @id key shall be interpreted as an IRI.
EXAMPLE 1 Serialization for non-URI simple value in RDF/X
...