rfc9264.original		rfc9264.txt
	Network Working Group E. Wilde		Internet Engineering Task Force (IETF) E. Wilde
	Internet-Draft Axway		Request for Comments: 9264 Axway
	Intended status: Standards Track H. Van de Sompel		Category: Standards Track H. Van de Sompel
	Expires: 6 November 2022 Data Archiving and Networked Services		ISSN: 2070-1721 Data Archiving and Networked Services
	5 May 2022		July 2022
	Linkset: Media Types and a Link Relation Type for Link Sets		Linkset: Media Types and a Link Relation Type for Link Sets
	draft-ietf-httpapi-linkset-10
	Abstract		Abstract
	This specification defines two formats and respective media types for		This specification defines two formats and associated media types for
	representing sets of links as stand-alone documents. One format is		representing sets of links as standalone documents. One format is
	JSON-based, the other aligned with the format for representing links		based on JSON, and the other is aligned with the format for
	in the HTTP "Link" header field. This specification also introduces		representing links in the HTTP "Link" header field. This
	a link relation type to support discovery of sets of links.		specification also introduces a link relation type to support the
			discovery of sets of links.
	Note to Readers
	Please discuss this draft on the "Building Blocks for HTTP APIs"
	mailing list (https://www.ietf.org/mailman/listinfo/httpapi).
	Online access to all versions and files is available on GitHub
	(https://github.com/ietf-wg-httpapi/linkset).
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This is an Internet Standards Track document.
	provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		This document is a product of the Internet Engineering Task Force
	and may be updated, replaced, or obsoleted by other documents at any		(IETF). It represents the consensus of the IETF community. It has
	time. It is inappropriate to use Internet-Drafts as reference		received public review and has been approved for publication by the
	material or to cite them other than as "work in progress."		Internet Engineering Steering Group (IESG). Further information on
			Internet Standards is available in Section 2 of RFC 7841.
	This Internet-Draft will expire on 6 November 2022.		Information about the current status of this document, any errata,
			and how to provide feedback on it may be obtained at
			https://www.rfc-editor.org/info/rfc9264.
	Copyright Notice		Copyright Notice
	Copyright (c) 2022 IETF Trust and the persons identified as the		Copyright (c) 2022 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents (https://trustee.ietf.org/		Provisions Relating to IETF Documents
	license-info) in effect on the date of publication of this document.		(https://trustee.ietf.org/license-info) in effect on the date of
	Please review these documents carefully, as they describe your rights		publication of this document. Please review these documents
	and restrictions with respect to this document. Code Components		carefully, as they describe your rights and restrictions with respect
	extracted from this document must include Revised BSD License text as		to this document. Code Components extracted from this document must
	described in Section 4.e of the Trust Legal Provisions and are		include Revised BSD License text as described in Section 4.e of the
	provided without warranty as described in the Revised BSD License.		Trust Legal Provisions and are provided without warranty as described
			in the Revised BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Terminology
	3. Use Cases and Motivation . . . . . . . . . . . . . . . . . . 3		3. Use Cases and Motivation
	3.1. Third-Party Links . . . . . . . . . . . . . . . . . . . . 4		3.1. Third-Party Links
	3.2. Challenges Writing to HTTP Link Header Field . . . . . . 5		3.2. Challenges Writing to the HTTP "Link" Header Field
	3.3. Large Number of Links . . . . . . . . . . . . . . . . . . 5		3.3. Large Number of Links
	4. Document Formats for Sets of Links . . . . . . . . . . . . . 5		4. Document Formats for Sets of Links
	4.1. HTTP Link Document Format: application/linkset . . . . . 7		4.1. HTTP Link Document Format: application/linkset
	4.2. JSON Document Format: application/linkset+json . . . . . 7		4.2. JSON Document Format: application/linkset+json
	4.2.1. Set of Links . . . . . . . . . . . . . . . . . . . . 8		4.2.1. Set of Links
	4.2.2. Link Context Object . . . . . . . . . . . . . . . . . 8		4.2.2. Link Context Object
	4.2.3. Link Target Object . . . . . . . . . . . . . . . . . 9		4.2.3. Link Target Object
	4.2.4. Link Target Attributes . . . . . . . . . . . . . . . 10		4.2.4. Link Target Attributes
	4.2.5. JSON Extensibility . . . . . . . . . . . . . . . . . 15		4.2.5. JSON Extensibility
	5. The "profile" parameter for media types to Represent Sets of		5. The "profile" Parameter for Media Types to Represent Sets of
	Links . . . . . . . . . . . . . . . . . . . . . . . . . . 15		Links
	6. The "linkset" Relation Type for Linking to a Set of Links . . 16		6. The "linkset" Relation Type for Linking to a Set of Links
	7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 17		7. Examples
	7.1. Set of Links Provided as application/linkset . . . . . . 17		7.1. Set of Links Provided as "application/linkset"
	7.2. Set of Links Provided as application/linkset+json . . . . 18		7.2. Set of Links Provided as "application/linkset+json"
	7.3. Discovering a Link Set via the "linkset" Link Relation		7.3. Discovering a Link Set via the "linkset" Link Relation Type
	Type . . . . . . . . . . . . . . . . . . . . . . . . . . 20		7.4. Link Set Profiles
	7.4. Link Set Profiles . . . . . . . . . . . . . . . . . . . . 21		7.4.1. Using a "profile" Attribute with a "linkset" Link
	7.4.1. Using a "profile" Attribute with a "linkset" Link . . 21		7.4.2. Using a "profile" Parameter with a Link Set Media Type
	7.4.2. Using a "profile" Parameter with a Link Set Media		7.4.3. Using a Link with a "profile" Link Relation Type
	Type . . . . . . . . . . . . . . . . . . . . . . . . 21		8. IANA Considerations
	7.4.3. Using a Link with a "profile" Link Relation Type . . 22		8.1. Link Relation Type: linkset
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23		8.2. Media Type: application/linkset
	8.1. Link Relation Type: linkset . . . . . . . . . . . . . . . 23		8.3. Media Type: application/linkset+json
	8.2. Media Type: application/linkset . . . . . . . . . . . . . 23		9. Security Considerations
	8.3. Media Type: application/linkset+json . . . . . . . . . . 24		10. References
	9. Security Considerations . . . . . . . . . . . . . . . . . . . 25		10.1. Normative References
	10. Normative References . . . . . . . . . . . . . . . . . . . . 26		10.2. Informative References
	11. Informative References . . . . . . . . . . . . . . . . . . . 27		Appendix A. JSON-LD Context
	Appendix A. JSON-LD Context . . . . . . . . . . . . . . . . . . 28		Acknowledgements
	Appendix B. Implementation Status . . . . . . . . . . . . . . . 33		Authors' Addresses
	B.1. GS1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
	B.2. FAIR Signposting Profile . . . . . . . . . . . . . . . . 34
	B.3. Open Journal Systems (OJS) . . . . . . . . . . . . . . . 34
	Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 34
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35
	1. Introduction		1. Introduction
	Resources on the Web often use typed Web Links [RFC8288], either		Resources on the Web often use typed Web Links [RFC8288], either
	embedded in resource representations, for example using the <link>		(1) embedded in resource representations -- for example, using the
	element for HTML documents, or conveyed in the HTTP "Link" header		<link> element for HTML documents or (2) conveyed in the HTTP "Link"
	field for documents of any media type. In some cases, however,		header field for documents of any media type. In some cases,
	providing links in this manner is impractical or impossible and		however, providing links in this manner is impractical or impossible,
	delivering a set of links as a stand-alone document is preferable.		and delivering a set of links as a standalone document is preferable.
	Therefore, this specification defines two formats for representing		Therefore, this specification defines two formats for representing
	sets of Web Links and their attributes as stand-alone documents. One		sets of Web Links and their attributes as standalone documents. One
	serializes links in the same format as used in the HTTP Link header		serializes links in the same format as the format used in the HTTP
	field, and the other serializes links in JSON. It also defines		"Link" header field, and the other serializes links in JSON. It also
	associated media types to represent sets of links, and the "linkset"		defines associated media types to represent sets of links, and the
	relation type that supports discovery of any resource that conveys a		"linkset" relation type to support the discovery of any resource that
	set of links as a stand-alone document.		conveys a set of links as a standalone document.
	2. Terminology		2. Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	This specification uses the terms "link context" and "link target" in		This specification uses the terms "link context" and "link target" in
	the same manner as [RFC8288].		the same manner that "Web Linking" [RFC8288] uses them.
	In the examples provided in this document, links in the HTTP "Link"		In the examples provided in this document, links in the HTTP "Link"
	header field are shown on separate lines in order to improve		header field are shown on separate lines in order to improve
	readability. Note, however, that as per Section 5.5 of		readability. Note, however, that as per Section 5.5 of "HTTP
	[I-D.ietf-httpbis-semantics], line breaks are deprecated in values		Semantics" [RFC9110], line breaks are deprecated in values for HTTP
	for HTTP fields; only whitespaces and tabs are supported as		fields; only whitespaces and tabs are supported as separators.
	separators.
	3. Use Cases and Motivation		3. Use Cases and Motivation
	The following sections describe use cases in which providing links by		The following sections describe use cases in which providing links by
	means of a standalone document instead of in an HTTP "Link" header		means of a standalone document instead of in an HTTP "Link" header
	field or as links embedded in the resource representation is		field or as links embedded in the resource representation is
	advantageous or necessary.		advantageous or necessary.
	For all scenarios, links could be provided by means of a stand-alone		For all scenarios, links could be provided by means of a standalone
	document that is formatted according to the JSON-based serialization,		document that is formatted according to the JSON-based serialization,
	the serialization aligned with the HTTP "Link" field format, or both.		the serialization aligned with the HTTP "Link" field format, or both.
	The former serialization is motivated by the widespread use of JSON		The former serialization is motivated by the widespread use of JSON
	and related tools, which suggests that handling sets of links		and related tools, which suggests that handling sets of links
	expressed as JSON documents should be attractive to developers. The		expressed as JSON documents should be attractive to developers. The
	latter serialization is provided for compatibility with the existing		latter serialization is provided for compatibility with the existing
	serialization used in the HTTP "Link" field and to allow reuse of		serialization used in the HTTP "Link" field and to allow the reuse of
	tools created to handle it.		tools created to handle it.
	It is important to keep in mind that when providing links by means of		It is important to keep in mind that when providing links by means of
	a standalone representation, other links can still be provided using		a standalone representation, other links can still be provided using
	other approaches, i.e. it is possible to combine various mechanisms		other approaches, i.e., it is possible to combine various mechanisms
	to convey links.		to convey links.
	3.1. Third-Party Links		3.1. Third-Party Links
	In some cases it is useful that links pertaining to a resource are		In some cases, it is useful that links pertaining to a resource are
	provided by a server other than the one that hosts the resource. For		provided by a server other than the one that hosts the resource. For
	example, this allows:		example, this allows:
	* Providing links in which the resource is involved not just as link		* Providing links in which the resource is involved not just as a
	context but also as link target, with a different resource being		link context but also as a link target, with a different resource
	the link context.		being the link context.
	* Providing links pertaining to the resource that the server hosting		* Providing links pertaining to the resource that the server hosting
	that resource is not aware of.		that resource is not aware of.
	* External management of links pertaining to the resource in a		* External management of links pertaining to the resource in a
	special-purpose link management service.		special-purpose link management service.
	In such cases, links pertaining to a resource can be provided by		In such cases, links pertaining to a resource can be provided by
	another, specific resource. That specific resource may be managed by		another, specific resource. That specific resource may be managed,
	the same or by another custodian as the resource to which the links		by the same custodian or by another custodian, as the resource to
	pertain. For clients intent on consuming links provided in that		which the links pertain. For clients intent on consuming links
	manner, it would be beneficial if the following conditions were met:		provided in that manner, it would be beneficial if the following
			conditions were met:
	* Links are provided in a document that uses a well-defined media		* Links are provided in a document that uses a well-defined media
	type.		type.
	* The resource to which the provided links pertain is able to link		* The resource to which the provided links pertain is able to link
	to the resource that provides these links using a well-known link		to the resource that provides these links using a well-known link
	relation type.		relation type.
	These requirements are addressed in this specification through the		These requirements are addressed in this specification through the
	definition of two media types and a link relation type, respectively.		definition of two media types and a link relation type, respectively.
	3.2. Challenges Writing to HTTP Link Header Field		3.2. Challenges Writing to the HTTP "Link" Header Field
	In some cases, it is not straightforward to write links to the HTTP		In some cases, it is not straightforward to write links to the HTTP
	"Link" header field from an application. This can, for example, be		"Link" header field from an application. This can, for example, be
	the case because not all required link information is available to		the case because not all required link information is available to
	the application or because the application does not have the		the application or because the application does not have the
	capability to directly write HTTP fields. In such cases, providing		capability to directly write HTTP fields. In such cases, providing
	links by means of a standalone document can be a solution. Making		links by means of a standalone document can be a solution. Making
	the resource that provides these links discoverable can be achieved		the resource that provides these links discoverable can be achieved
	by means of a typed link.		by means of a typed link.
	skipping to change at page 5, line 27 ¶		skipping to change at line 198 ¶
	When conveying links in an HTTP "Link" header field, it is possible		When conveying links in an HTTP "Link" header field, it is possible
	for the size of the HTTP response fields to become unpredictable.		for the size of the HTTP response fields to become unpredictable.
	This can be the case when links are determined dynamically in a		This can be the case when links are determined dynamically in a
	manner dependent on a range of contextual factors. It is possible to		manner dependent on a range of contextual factors. It is possible to
	statically configure a web server to correctly handle large HTTP		statically configure a web server to correctly handle large HTTP
	response fields by specifying an upper bound for their size. But		response fields by specifying an upper bound for their size. But
	when the number of links is unpredictable, estimating a reliable		when the number of links is unpredictable, estimating a reliable
	upper bound is challenging.		upper bound is challenging.
	Section 15 of HTTP [I-D.ietf-httpbis-semantics] defines error codes		Section 15 of "HTTP Semantics" [RFC9110] defines error codes related
	related to excess communication by the user agent ("413 Request		to excess communication by the user agent ("413 Content Too Large"
	Entity Too Large" and "414 Request-URI Too Long"), but no specific		and "414 URI Too Long"), but no specific error codes are defined to
	error codes are defined to indicate that response field content		indicate that response field content exceeds the upper bound that can
	exceeds the upper bound that can be handled by the server and thus		be handled by the server and thus has been truncated. As a result,
	has been truncated. As a result, applications take counter measures		applications take countermeasures aimed at controlling the size of
	aimed at controlling the size of the HTTP "Link" header field, for		the HTTP "Link" header field -- for example, by limiting the links
	example by limiting the links they provide to those with select		they provide to those with select relation types, thereby limiting
	relation types, thereby limiting the value of the HTTP "Link" header		the value of the HTTP "Link" header field to clients. Providing
	field to clients. Providing links by means of a standalone document		links by means of a standalone document overcomes challenges related
	overcomes challenges related to the unpredictable (to the web server		to the unpredictable (to the web server implementation) nature of the
	implementation) nature of the size of HTTP "Link" header fields.		size of HTTP "Link" header fields.
	4. Document Formats for Sets of Links		4. Document Formats for Sets of Links
	This section specifies two document formats to convey a set of links.		This section specifies two document formats to convey a set of links.
	Both are based on the abstract model specified in Section 2 of Web		Both are based on the abstract model specified in Section 2 of "Web
	Linking [RFC8288] that defines a link as consisting of a "link		Linking" [RFC8288], which defines a link as consisting of a "link
	context", a "link relation type", a "link target", and optional		context", a "link relation type", a "link target", and optional
	"target attributes":		"target attributes":
	* The format defined in Section 4.1 is nearly identical to the field		* The format defined in Section 4.1 is nearly identical to the field
	value of the HTTP "Link" header field as specified in Section 3 of		value of the HTTP "Link" header field as specified in Section 3 of
	[RFC8288].		[RFC8288].
	* The format defined in Section 4.2 is expressed in JSON [RFC8259].		* The format defined in Section 4.2 is expressed in JSON [RFC8259].
	Links provided in the HTTP Link header are intended to be used in the		Links provided in the HTTP "Link" header field are intended to be
	context of an HTTP interaction and contextual information that is		used in the context of an HTTP interaction, and contextual
	available during an interaction is used to correctly interpret them.		information that is available during an interaction is used to
	Links provided in link sets, however, can be re-used outside of an		correctly interpret them. Links provided in link sets, however, can
	HTTP interaction, when no such contextual information is available.		be reused outside of an HTTP interaction, when no such contextual
	As a result, implementers of link sets should strive to make them		information is available. As a result, implementers of link sets
	self-contained by adhering to the following recommendations.		should strive to make them self-contained by adhering to the
			following recommendations.
	For links provided in the HTTP Link header that have no anchor or		For links provided in the HTTP "Link" header field that have no
	that use relative references, the URI of the resource that delivers		anchor or that use relative references, the URI of the resource that
	the links provides the contextual information that is needed for		delivers the links provides the contextual information that is needed
	their correct interpretation. In order to support use cases where		for their correct interpretation. In order to support use cases
	link set documents are re-used outside the context of an HTTP		where link set documents are reused outside the context of an HTTP
	interaction, it is RECOMMENDED to make them self-contained by		interaction, it is RECOMMENDED to make them self-contained by
	adhering to the following guidelines:		adhering to the following guidelines:
	* For every link provided in the set of links, explicitly provide		* For every link provided in the set of links, explicitly provide
	the link context using the "anchor" attribute.		the link context using the "anchor" attribute.
	* For link context ("anchor" attribute) and link target ("href"		* For the link context ("anchor" attribute) and link target ("href"
	attribute), use URI references that are not relative references		attribute), use URI references that are not relative references
	(as defined in Section 4.1 of [RFC3986]).		(as defined in Section 4.1 of [RFC3986]).
	If these recommendations are not followed, interpretation of links in		If these recommendations are not followed, the interpretation of
	link set documents will depend on which URI is used as context.		links in link set documents will depend on which URI is used as the
			context.
	For a "title" attribute provided on a link in the HTTP Link header,		For a "title" attribute provided on a link in the HTTP "Link" header
	the language in which the title is expressed is provided by the		field, the language in which the title is expressed is provided by
	Content-Language header of the HTTP interaction with the resource		the "Content-Language" header field of the HTTP interaction with the
	that delivers the links. This does not apply to "title" attributes		resource that delivers the links. This does not apply to "title"
	provided for links in link set documents because that would constrain		attributes provided for links in link set documents because that
	all links in a link set to having a single title language and would		would constrain all links in a link set to having a single title
	not support determining title languages when a link set is used		language and would not support determining title languages when a
	outside of an HTTP interaction. In order to support use cases where		link set is used outside of an HTTP interaction. In order to support
	link set documents are re-used outside the context of an HTTP		use cases where link set documents are reused outside the context of
	interaction, it is RECOMMENDED to make them self-contained by using		an HTTP interaction, it is RECOMMENDED to make them self-contained by
	the "title*" attribute instead of the "title" attribute because		using the "title*" attribute instead of the "title" attribute because
	"title*" allows expressing the title language as part of its value by		"title*" allows expressing the title language as part of its value by
	means of a language tag. With this regard, note that language tags		means of a language tag. Note that, in this regard, language tags
	are matched case-insensitively (see Section 2.1.1 of [RFC5646]). If		are matched case insensitively (see Section 2.1.1 of [RFC5646]). If
	this recommendation is not followed, accurately determining the		this recommendation is not followed, accurately determining the
	language of titles provided on links in link set documents will not		language of titles provided on links in link set documents will not
	be possible.		be possible.
	Note also that Section 3.3 of [RFC8288] deprecates the "rev"		Note also that Section 3.3 of [RFC8288] deprecates the "rev"
	construct that was provided by [RFC5988] as a means to express links		construct that was provided by [RFC5988] as a means to express links
	with a directionality that is the inverse of direct links that use		with a directionality that is the inverse of direct links that use
	the "rel" construct. In both serializations for link sets defined		the "rel" construct. In both serializations for link sets defined
	here, inverse links may be represented as direct links using the		here, inverse links may be represented as direct links using the
	"rel" construct and by switching the roles of the resources involved		"rel" construct and by switching the roles of the resources involved
	in the link.		in the link.
	4.1. HTTP Link Document Format: application/linkset		4.1. HTTP Link Document Format: application/linkset
	This document format is nearly identical to the field value of the		This document format is nearly identical to the field value of the
	HTTP "Link" header field as defined in Section 3 of [RFC8288], more		HTTP "Link" header field as defined in Section 3 of [RFC8288], more
	specifically by its ABNF [RFC5234] production rule for "Link" and		specifically by its ABNF [RFC5234] production rule for "Link" and its
	subsequent ones. It differs from the format for field values of the		subsequent rules. It differs from the format for field values of the
	HTTP "Link" header only in that not only spaces and horizontal tabs		HTTP "Link" header field only in that not only spaces and horizontal
	are allowed as separators but also newline characters as a means to		tabs are allowed as separators but also newline characters as a means
	improve readability for humans. The use of non-ASCII characters in		to improve readability for humans. The use of non-ASCII characters
	the field value of the HTTP "Link" Header field is not allowed, and		in the field value of the HTTP "Link" header field is not allowed and
	as such is also not allowed in "application/linkset" link sets.		as such is also not allowed in "application/linkset" link sets.
	The assigned media type for this format is "application/linkset".		The assigned media type for this format is "application/linkset".
	When converting an "application/linkset" document to a field value		When converting an "application/linkset" document to a field value
	for the HTTP "Link" header, newline characters MUST be removed or		for the HTTP "Link" header field, newline characters MUST be removed
	MUST be replaced by white space (SP) in order to comply with		or MUST be replaced by whitespace (SP) in order to comply with
	Section 5.5 of [I-D.ietf-httpbis-semantics].		Section 5.5 of [RFC9110].
	Implementers of "application/linkset" link sets should strive to make		Implementers of "application/linkset" link sets should strive to make
	them self-contained by following the recommendations regarding their		them self-contained by following the recommendations provided in
	use outside the context of an HTTP interaction provided in Section 4.		Section 4 regarding their use outside the context of an HTTP
			interaction.
	It should be noted that the "application/linkset" format specified		It should be noted that the "application/linkset" format specified
	here is different from the "application/link-format" format specified		here is different from the "application/link-format" format specified
	in [RFC6690] in that the former fully matches the field value of the		in [RFC6690] in that the former fully matches the field value of the
	HTTP "Link" header field as defined in Section 3 of [RFC8288],		HTTP "Link" header field as defined in Section 3 of [RFC8288],
	whereas the latter introduces constraints on that definition to meet		whereas the latter introduces constraints on that definition to meet
	requirements for Constrained RESTful Environments (CoRE).		requirements for Constrained RESTful Environments (CoRE).
	4.2. JSON Document Format: application/linkset+json		4.2. JSON Document Format: application/linkset+json
	This document format uses JSON [RFC8259] as the syntax to represent a		This document format uses JSON [RFC8259] as the syntax to represent a
	set of links. The set of links follows the abstract model defined by		set of links. The set of links follows the abstract model defined by
	Web Linking Section 2 of [RFC8288].		Section 2 of [RFC8288].
	The assigned media type for this format is "application/		The assigned media type for this format is "application/
	linkset+json".		linkset+json".
	In the interests of interoperability "application/linkset+json" link		In the interests of interoperability, "application/linkset+json" link
	sets MUST be encoded using UTF-8 as per Section 8.1 of [RFC8259].		sets MUST be encoded using UTF-8 as per Section 8.1 of [RFC8259].
	Implementers of "application/linkset+json" link sets should strive to		Implementers of "application/linkset+json" link sets should strive to
	make them self-contained by following the recommendations regarding		make them self-contained by following the recommendations provided in
	their use outside the context of an HTTP interaction provided in		Section 4 regarding their use outside the context of an HTTP
	Section 4.		interaction.
	The "application/linkset+json" serialization allows for OPTIONAL		The "application/linkset+json" serialization allows for OPTIONAL
	support of a JSON-LD serialization. This can be achieved by adding		support of a JSON-LD serialization. This can be achieved by adding
	an appropriate context to the "application/linkset+json"		an appropriate context to the "application/linkset+json"
	serialization using the approach described in Section 6.8. of		serialization using the approach described in Section 6.1 of
	[W3C.REC-json-ld-20140116]. Communities of practice can decide which		[W3C.REC-json-ld]. Communities of practice can decide which context
	context best meets their application needs. Appendix A shows an		best meets their application needs. Appendix A shows an example of a
	example of a possible context that, when added to a JSON		possible context that, when added to a JSON serialization, allows it
	serialization, allows it to be interpreted as Resource Description		to be interpreted as Resource Description Framework (RDF) data
	Framework (RDF) [W3C.REC-rdf11-concepts-20140225] data.		[W3C.REC-rdf11-concepts].
	4.2.1. Set of Links		4.2.1. Set of Links
	In the JSON representation of a set of links:		In the JSON representation of a set of links:
	* A set of links is represented in JSON as an object which MUST		* A set of links is represented in JSON as an object that MUST
	contain "linkset" as its sole member.		contain "linkset" as its sole member.
	* The value of the "linkset" member is an array in which a distinct		* The value of the "linkset" member is an array in which a distinct
	JSON object - the "link context object" (see Section 4.2.2) - is		JSON object -- the "link context object" (see Section 4.2.2) -- is
	used to represent links that have the same link context.		used to represent links that have the same link context.
	* Even if there is only one link context object, it MUST be wrapped		* Even if there is only one link context object, it MUST be wrapped
	in an array.		in an array.
	4.2.2. Link Context Object		4.2.2. Link Context Object
	In the JSON representation one or more links that have the same link		In the JSON representation, one or more links that have the same link
	context are represented by a JSON object, the link context object. A		context are represented by a JSON object -- the link context object.
	link context object adheres to the following rules:		A link context object adheres to the following rules:
	* Each link context object MAY contain an "anchor" member with a		* Each link context object MAY contain an "anchor" member with a
	value that represents the link context. If present, this value		value that represents the link context. If present, this value
	MUST be a URI reference and SHOULD NOT be a relative reference as		MUST be a URI reference and SHOULD NOT be a relative reference as
	defined in Section 4.1 of [RFC3986].		defined in Section 4.1 of [RFC3986].
	* For each distinct relation type that the link context has with		* For each distinct relation type that the link context has with
	link targets, a link context object MUST contain an additional		link targets, a link context object MUST contain an additional
	member. The value of this member is an array in which a distinct		member. The value of this member is an array in which a distinct
	JSON object - the "link target object" (see Section 4.2.3) - MUST		JSON object -- the "link target object" (see Section 4.2.3) --
	be used for each link target for which the relationship with the		MUST be used for each link target for which the relationship with
	link context (value of the encompassing anchor member) applies.		the link context (value of the encompassing "anchor" member)
	The name of this member expresses the relation type of the link as		applies. The name of this member expresses the relation type of
	follows:		the link as follows:
	- For registered relation types (Section 2.1.1 of [RFC8288]), the		- For registered relation types (Section 2.1.1 of [RFC8288]), the
	name of this member is the registered name of the relation		name of this member is the registered name of the relation
	type.		type.
	- For extension relation types (Section 2.1.2 of [RFC8288]), the		- For extension relation types (Section 2.1.2 of [RFC8288]), the
	name of this member is the URI that uniquely represents the		name of this member is the URI that uniquely represents the
	relation type.		relation type.
	* Even if there is only one link target object it MUST be wrapped in		* Even if there is only one link target object, it MUST be wrapped
	an array.		in an array.
	4.2.3. Link Target Object		4.2.3. Link Target Object
	In the JSON representation a link target is represented by a JSON		In the JSON representation, a link target is represented by a JSON
	object, the link target object. A link target object adheres to the		object -- the link target object. A link target object adheres to
	following rules:		the following rules:
	* Each link target object MUST contain an "href" member with a value		* Each link target object MUST contain an "href" member with a value
	that represents the link target. This value MUST be a URI		that represents the link target. This value MUST be a URI
	reference and SHOULD NOT be a relative reference as defined in		reference and SHOULD NOT be a relative reference as defined in
	Section 4.1 of [RFC3986]. Cases where the href member is present,		Section 4.1 of [RFC3986]. Cases where the "href" member is
	but no value is provided for it (i.e. the resource providing the		present but no value is provided for it (i.e., the resource
	set of links is the target of the link in the link target object)		providing the set of links is the target of the link in the link
	MUST be handled by providing an "href" member with an empty string		target object) MUST be handled by providing an "href" member with
	as its value ("href": "").		an empty string as its value ("href": "").
	* In many cases, a link target is further qualified by target		* In many cases, a link target is further qualified by target
	attributes. Various types of attributes exist and they are		attributes. Various types of attributes exist, and they are
	conveyed as additional members of the link target object as		conveyed as additional members of the link target object as
	detailed in Section 4.2.4.		detailed in Section 4.2.4.
	The following example of a JSON-serialized set of links represents		The following example of a JSON-serialized set of links represents
	one link with its core components: link context, link relation type,		one link with its core components: link context, link relation type,
	and link target.		and link target.
	{ "linkset":		{ "linkset":
	[		[
	{ "anchor": "https://example.net/bar",		{ "anchor": "https://example.net/bar",
	"next": [		"next": [
	{"href": "https://example.com/foo"}		{"href": "https://example.com/foo"}
	]		]
	}		}
	]		]
	}		}
	Figure 1		Figure 1: Simple linkset example
	The following example of a JSON-serialized set of links represents		The following example of a JSON-serialized set of links represents
	two links that share link context and relation type but have		two links that share a link context and relation type but have
	different link targets.		different link targets.
	{ "linkset":		{ "linkset":
	[		[
	{ "anchor": "https://example.net/bar",		{ "anchor": "https://example.net/bar",
	"item": [		"item": [
	{"href": "https://example.com/foo1"},		{"href": "https://example.com/foo1"},
	{"href": "https://example.com/foo2"}		{"href": "https://example.com/foo2"}
	]		]
	}		}
	]		]
	}		}
	Figure 2		Figure 2: Linkset with two links with the same context
	The following example shows a set of links that represents two links,		The following example shows a set of links that represents two links,
	each with a different link context, link target, and relation type.		each with a different link context, link target, and relation type.
	One relation type is registered, the other is an extension relation		One relation type is registered, and the other is an extension
	type.		relation type.
	{ "linkset":		{ "linkset":
	[		[
	{ "anchor": "https://example.net/bar",		{ "anchor": "https://example.net/bar",
	"next": [		"next": [
	{"href": "https://example.com/foo1"}		{"href": "https://example.com/foo1"}
	]		]
	},		},
	{ "anchor": "https://example.net/boo",		{ "anchor": "https://example.net/boo",
	"https://example.com/relations/baz" : [		"https://example.com/relations/baz" : [
	{"href": "https://example.com/foo2"}		{"href": "https://example.com/foo2"}
	]		]
	}		}
	]		]
	}		}
	Figure 3		Figure 3: Linkset with two links with different contexts
	4.2.4. Link Target Attributes		4.2.4. Link Target Attributes
	A link may be further qualified by target attributes as defined by		A link may be further qualified by target attributes as defined by
	Section 2 of Web Linking [RFC8288]. Three types of attributes exist:		Section 2 of [RFC8288]. Three types of attributes exist:
	* Serialisation-defined attributes described in Section 3.4.1 of Web		* Serialization-defined attributes as described in Section 3.4.1 of
	Linking [RFC8288].		[RFC8288].
	* Extension attributes defined and used by communities as allowed by		* Extension attributes defined and used by communities as allowed by
	Section 3.4.2 of [RFC8288].		Section 3.4.2 of [RFC8288].
	* Internationalized versions of the "title" attribute defined by		* Internationalized versions of the "title" attribute as defined by
	[RFC8288] and of extension attributes allowed by Section 3.4 of		[RFC8288] and of extension attributes allowed by Section 3.4 of
	[RFC8288].		[RFC8288].
	The handling of these different types of attributes is described in		The handling of these different types of attributes is described in
	the sections below.		the sections below.
	4.2.4.1. Target Attributes Defined by Web Linking		4.2.4.1. Target Attributes Defined by Web Linking
	Section 3.4.1 of [RFC8288] defines the following target attributes		Section 3.4.1 of [RFC8288] defines the following target attributes
	that may be used to annotate links: "hreflang", "media", "title",		that may be used to annotate links: "hreflang", "media", "title",
	"title*", and "type"; these target attributes follow different		"title*", and "type"; these target attributes follow different
	occurrence and value patterns. In the JSON representation, these		occurrence and value patterns. In the JSON representation, these
	attributes MUST be conveyed as additional members of the link target		attributes MUST be conveyed as additional members of the link target
	object as follows:		object as follows:
	* "hreflang": The "hreflang" target attribute, defined as optional		"hreflang": The "hreflang" target attribute, defined as optional and
	and repeatable by [RFC8288], MUST be represented by an "hreflang"		repeatable by [RFC8288], MUST be represented by an "hreflang"
	member, and its value MUST be an array (even if there only is one		member, its value MUST be an array (even if there is only one
	value to be represented), and each value in that array MUST be a		value to be represented), and each value in that array MUST be a
	string - representing one value of the "hreflang" target attribute		string -- representing one value of the "hreflang" target
	for a link - which follows the same model as in the [RFC8288]		attribute for a link -- that follows the same model as the syntax
	syntax.		discussed in [RFC8288].
	* "media": The "media" target attribute, defined as optional and not		"media": The "media" target attribute, defined as optional and not
	repeatable by [RFC8288], MUST be represented by a "media" member		repeatable by [RFC8288], MUST be represented by a "media" member
	in the link target object, and its value MUST be a string that		in the link target object, and its value MUST be a string that
	follows the same model as in the [RFC8288] syntax.		follows the same model as the syntax discussed in [RFC8288].
	* "type": The "type" target attribute, defined as optional and not
	repeatable by [RFC8288], MUST be represented by a "type" member in
	the link target object, and its value MUST be a string that
	follows the same model as in the [RFC8288] syntax.
	* "title": The "title" target attribute, defined as optional and not		"title": The "title" target attribute, defined as optional and not
	repeatable by [RFC8288], MUST be represented by a "title" member		repeatable by [RFC8288], MUST be represented by a "title" member
	in the link target object, and its value MUST be a JSON string.		in the link target object, and its value MUST be a JSON string.
	* "title*": The "title*" target attribute, defined as optional and		"title*": The "title*" target attribute, defined as optional and not
	not repeatable by [RFC8288], is motivated by character encoding		repeatable by [RFC8288], is motivated by character encoding and
	and language issues and follows the model defined in [RFC8187].		language issues and follows the model defined in [RFC8187]. The
	The details of the JSON representation that applies to title* are		details of the JSON representation that applies to "title*" are
	described in Section 4.2.4.2.		described in Section 4.2.4.2.
	The following example illustrates how the repeatable "hreflang" and		"type": The "type" target attribute, defined as optional and not
	the not repeatable "type" target attributes are represented in a link		repeatable by [RFC8288], MUST be represented by a "type" member in
	target object.		the link target object, and its value MUST be a string that
			follows the same model as the syntax discussed in [RFC8288].
			The following example illustrates how the "hreflang" (repeatable)
			target attribute and the "type" (not repeatable) target attribute are
			represented in a link target object.
	{ "linkset":		{ "linkset":
	[		[
	{ "anchor": "https://example.net/bar",		{ "anchor": "https://example.net/bar",
	"next": [		"next": [
	{ "href": "https://example.com/foo",		{ "href": "https://example.com/foo",
	"type": "text/html",		"type": "text/html",
	"hreflang": [ "en" , "de" ]		"hreflang": [ "en" , "de" ]
	}		}
	]		]
	}		}
	]		]
	}		}
	Figure 4		Figure 4: Linkset with "hreflang" and "type" target attributes
	4.2.4.2. Internationalized Target Attributes		4.2.4.2. Internationalized Target Attributes
	In addition to the target attributes described in Section 4.2.4.1,		In addition to the target attributes described in Section 4.2.4.1,
	Section 3.4 of [RFC8288] also supports attributes that follow the		Section 3.4 of [RFC8288] also supports attributes that follow the
	content model of [RFC8187]. In [RFC8288], these target attributes		content model of [RFC8187]. In [RFC8288], these target attributes
	are recognizable by the use of a trailing asterisk in the attribute		are recognizable by the use of a trailing asterisk in the attribute
	name, such as "title*". The content model of [RFC8187] uses a		name, such as "title*". The content model of [RFC8187] uses a
	string-based microsyntax that represents the character encoding, an		string-based microsyntax that represents the character encoding, an
	optional language tag, and the escaped attribute value encoded		optional language tag, and the escaped attribute value encoded
	according to the specified character encoding.		according to the specified character encoding.
	The JSON serialization for these target attributes MUST be as		The JSON serialization for these target attributes MUST be as
	follows:		follows:
	* An internationalized target attribute is represented as a member		* An internationalized target attribute is represented as a member
	of the link context object with the same name (including the *) as		of the link context object with the same name (including the "*")
	the attribute.		as the attribute.
	* The character encoding information as prescribed by [RFC8187] is		* The character encoding information as prescribed by [RFC8187] is
	not preserved; instead, the content of the internationalized		not preserved; instead, the content of the internationalized
	attribute is represented as a JSON string.		attribute is represented as a JSON string.
	* The value of the internationalized target attribute is an array		* The value of the internationalized target attribute is an array
	that contains one or more JSON objects. The name of one member of		that contains one or more JSON objects. The name of one member of
	such JSON object is "value" and its value is the actual content		such JSON objects is "value", and its value is the actual content
	(in its unescaped version) of the internationalized target		(in its unescaped version) of the internationalized target
	attribute, i.e. the value of the attribute from which the encoding		attribute, i.e., the value of the attribute from which the
	and language information are removed. The name of another,		encoding and language information are removed. The name of
	optional, member of such JSON object is "language" and its value		another, optional member of such JSON objects is "language", and
	is the language tag [RFC5646] for the language in which the		its value is the language tag [RFC5646] for the language in which
	attribute content is conveyed.		the attribute content is conveyed.
	The following example illustrates how the "title*" target attribute		The following example illustrates how the "title*" target attribute
	defined by Section 3.4.1 of [RFC8288] is represented in a link target		as defined by Section 3.4.1 of [RFC8288] is represented in a link
	object.		target object.
	{ "linkset":		{ "linkset":
	[		[
	{ "anchor": "https://example.net/bar",		{ "anchor": "https://example.net/bar",
	"next": [		"next": [
	{ "href": "https://example.com/foo",		{ "href": "https://example.com/foo",
	"type": "text/html",		"type": "text/html",
	"hreflang": [ "en" , "de" ],		"hreflang": [ "en" , "de" ],
	"title": "Next chapter",		"title": "Next chapter",
	"title*": [ { "value": "nächstes Kapitel" ,		"title*": [ { "value": "nächstes Kapitel" ,
	"language" : "de" } ]		"language" : "de" } ]
	}		}
	]		]
	}		}
	]		]
	}		}
	Figure 5		Figure 5: Linkset with "title" and "title*" target attributes
	The above example assumes that the German title contains an umlaut		The above example assumes that the German title contains an umlaut
	character (in the original syntax it would be encoded as title*=UTF-		character (in the original syntax, it would be encoded as title*=UTF-
	8'de'n%c3%a4chstes%20Kapitel), which gets encoded in its unescaped		8'de'n%c3%a4chstes%20Kapitel), which gets encoded in its unescaped
	form in the JSON representation. Implementations MUST properly		form in the JSON representation. Implementations MUST properly
	decode/encode internationalized target attributes that follow the		decode/encode internationalized target attributes that follow the
	model of [RFC8187] when transcoding between the "application/linkset"		model of [RFC8187] when transcoding between the "application/linkset"
	and the "application/linkset+json" formats.		format and the "application/linkset+json" format.
	4.2.4.3. Extension Target Attributes		4.2.4.3. Extension Target Attributes
	Extension target attributes are attributes that are not defined by		Extension target attributes (e.g., as listed in Section 4.2.4.1) are
	Section 3.4.1 of [RFC8288] (as listed in Section 4.2.4.1), but are		attributes that are not defined by Section 3.4.1 of [RFC8288] but are
	nevertheless used to qualify links. They can be defined by		nevertheless used to qualify links. They can be defined by
	communities in any way deemed necessary, and it is up to them to make		communities in any way deemed necessary, and it is up to them to make
	sure their usage is understood by target applications. However,		sure their usage is understood by target applications. However,
	lacking standardization, there is no interoperable understanding of		lacking standardization, there is no interoperable understanding of
	these extension attributes. One important consequence is that their		these extension attributes. One important consequence is that their
	cardinality is unknown to generic applications. Therefore, in the		cardinality is unknown to generic applications. Therefore, in the
	JSON serialization, all extension target attributes are treated as		JSON serialization, all extension target attributes are treated as
	repeatable.		repeatable.
	The JSON serialization for these target attributes MUST be as		The JSON serialization for these target attributes MUST be as
	follows:		follows:
	* An extension target attribute is represented as a member of the		* An extension target attribute is represented as a member of the
	link target object with the same name as the attribute, including		link target object with the same name as the attribute, including
	the * if applicable.		the "*" if applicable.
	* The value of an extension attribute MUST be represented by an		* The value of an extension attribute MUST be represented by an
	array, even if there only is one value to be represented.		array, even if there is only one value to be represented.
	* If the extension target attribute does not have a name with a		* If the extension target attribute does not have a name with a
	trailing asterisk, then each value in that array MUST be a JSON		trailing asterisk, then each value in that array MUST be a JSON
	string that represents one value of the attribute.		string that represents one value of the attribute.
	* If the extension attribute has a name with a trailing asterisk (it		* If the extension attribute has a name with a trailing asterisk (it
	follows the content model of [RFC8187]), then each value in that		follows the content model of [RFC8187]), then each value in that
	array MUST be a JSON object. The value of each such JSON object		array MUST be a JSON object. The value of each such JSON object
	MUST be structured as described in Section 4.2.4.2.		MUST be structured as described in Section 4.2.4.2.
	The example shows a link target object with three extension target		The following example shows a link target object with three extension
	attributes. The value for each extension target attribute is an		target attributes. The value for each extension target attribute is
	array. The two first are regular extension target attributes, with		an array. The first two are regular extension target attributes,
	the first one ("foo") having only one value and the second one		with the first one ("foo") having only one value and the second one
	("bar") having two. The last extension target attribute ("baz*")		("bar") having two. The last extension target attribute ("baz*")
	follows the naming rule of [RFC8187] and therefore is encoded		follows the naming rule of [RFC8187] and therefore is encoded
	according to the serialization described in Section 4.2.4.2.		according to the serialization described in Section 4.2.4.2.
	{ "linkset":		{ "linkset":
	[		[
	{ "anchor": "https://example.net/bar",		{ "anchor": "https://example.net/bar",
	"next": [		"next": [
	{ "href": "https://example.com/foo",		{ "href": "https://example.com/foo",
	"type": "text/html",		"type": "text/html",
	"foo": [ "foovalue" ],		"foo": [ "foovalue" ],
	"bar": [ "barone", "bartwo" ],		"bar": [ "barone", "bartwo" ],
	"baz*": [ { "value": "bazvalue" ,		"baz*": [ { "value": "bazvalue" ,
	"language" : "en" } ]		"language" : "en" } ]
	}		}
	]		]
	}		}
	]		]
	}		}
	Figure 6
			Figure 6: Linkset with extension target attributes
	4.2.5. JSON Extensibility		4.2.5. JSON Extensibility
	The Web linking model ([RFC8288]) provides for the use of extension		The Web Linking model [RFC8288] provides for the use of extension
	target attributes as discussed in Section 4.2.4.3. The use of other		target attributes as discussed in Section 4.2.4.3. The use of other
	forms of extensions is NOT RECOMMENDED. Limiting the JSON format in		forms of extensions is NOT RECOMMENDED. Limiting the JSON format in
	this way allows to unambiguously round trip between links provided in		this way allows unambiguous round trips between links provided in the
	the HTTP "Link" header field, sets of links serialized according to		HTTP "Link" header field, sets of links serialized according to the
	the "application/linkset" format, and sets of links serialized		"application/linkset" format, and sets of links serialized according
	according to the "application/linkset+json" format.		to the "application/linkset+json" format.
	Cases may exist in which the use of extensions other than those of		Cases may exist in which the use of extensions other than those
	Section 4.2.4.3 may be useful. For example, when a link set		discussed in Section 4.2.4.3 may be useful -- for example, when a
	publisher needs to include descriptive or technical metadata for		link set publisher needs to include descriptive or technical metadata
	internal consumption. In case such extensions are used they MUST NOT		for internal consumption. If such extensions are used, they MUST NOT
	change the semantics of the JSON members defined in this		change the semantics of the JSON members defined in this
	specification. Agents that consume JSON linkset documents can safely		specification. Agents that consume JSON linkset documents can safely
	ignore such extensions.		ignore such extensions.
	5. The "profile" parameter for media types to Represent Sets of Links		5. The "profile" Parameter for Media Types to Represent Sets of Links
	As a means to convey specific constraints or conventions (as per		As a means to convey specific constraints or conventions (as per
	[RFC6906]) that apply to a link set document, the "profile" parameter		[RFC6906]) that apply to a link set document, the "profile" parameter
	MAY be used in conjunction with the media types "application/linkset"		MAY be used in conjunction with the media types "application/linkset"
	and "application/linkset+json" detailed in Section 4.1 and		and "application/linkset+json" as detailed in Sections 4.1 and 4.2,
	Section 4.2, respectively. For example, the parameter could be used		respectively. For example, the parameter could be used to indicate
	to indicate that a link set uses a specific, limited set of link		that a link set uses a specific, limited set of link relation types.
	relation types.
	The value of the "profile" parameter MUST be a non-empty list of		The value of the "profile" parameter MUST be a non-empty list of
	space-separated URIs, each of which identifies specific constraints		space-separated URIs, each of which identifies specific constraints
	or conventions that apply to the link set document. When providing		or conventions that apply to the link set document. When providing
	multiple profile URIs, care should be taken that the corresponding		multiple profile URIs, care should be taken that the corresponding
	profiles are not conflicting. Profile URIs MAY be registered in the		profiles are not conflicting. Profile URIs MAY be registered in the
	IANA Profile URI Registry in the manner specified by [RFC7284].		IANA's "Profile URIs" registry in the manner specified by [RFC7284].
	The presence of a "profile" parameter in conjunction with the		The presence of a "profile" parameter in conjunction with the
	"application/linkset" and "application/linkset+json" media types does		"application/linkset" and "application/linkset+json" media types does
	not change the semantics of a link set. As such, clients with and		not change the semantics of a link set. As such, clients with and
	without knowledge of profile URIs can use the same representation.		without knowledge of profile URIs can use the same representation.
	Section 7.4.2 shows an example of using the "profile" parameter in		Section 7.4.2 shows an example of using the "profile" parameter in
	conjunction with the "application/linkset+json" media type.		conjunction with the "application/linkset+json" media type.
	6. The "linkset" Relation Type for Linking to a Set of Links		6. The "linkset" Relation Type for Linking to a Set of Links
	skipping to change at page 16, line 24 ¶		skipping to change at line 712 ¶
	A resource MAY provide more than one link with a "linkset" relation		A resource MAY provide more than one link with a "linkset" relation
	type. Multiple such links can refer to the same set of links		type. Multiple such links can refer to the same set of links
	expressed using different media types, or to different sets of links,		expressed using different media types, or to different sets of links,
	potentially provided by different third-party services.		potentially provided by different third-party services.
	The set of links provided by the resource that is the target of a		The set of links provided by the resource that is the target of a
	"linkset" link may contain links in which the resource that is the		"linkset" link may contain links in which the resource that is the
	context of the "linkset" link does not participate. User agents MUST		context of the "linkset" link does not participate. User agents MUST
	process each link in the link set independently, including processing		process each link in the link set independently, including processing
	of link context and link target, and MAY ignore links from the link		of the link context and link target, and MAY ignore links from the
	set in which the context of the "linkset" link does not participate.		link set in which the context of the "linkset" link does not
			participate.
	A user agent that follows a "linkset" link and obtains links for		A user agent that follows a "linkset" link and obtains links for
	which anchors and targets are expressed as relative references (as		which anchors and targets are expressed as relative references (as
	per Section 4.1 of [RFC3986]) MUST determine what the context is for		per Section 4.1 of [RFC3986]) MUST determine what the context is for
	these links; it SHOULD ignore links for which it is unable to		these links; it SHOULD ignore links for which it is unable to
	unambiguously make that determination.		unambiguously make that determination.
	As a means to convey specific constraints or conventions (as per		As a means to convey specific constraints or conventions (as per
	[RFC6906]) that apply to a link set document, the "profile" attribute		[RFC6906]) that apply to a link set document, the "profile" attribute
	MAY be used in conjunction with the "linkset" link relation type.		MAY be used in conjunction with the "linkset" link relation type.
	For example, the attribute could be used to indicate that a link set		For example, the attribute could be used to indicate that a link set
	uses a specific, limited set of link relation types. The value of		uses a specific, limited set of link relation types. The value of
	the "profile" attribute MUST be a non-empty list of space-separated		the "profile" attribute MUST be a non-empty list of space-separated
	URIs, each of which identifies specific constraints or conventions		URIs, each of which identifies specific constraints or conventions
	that apply to the link set document. Profile URIs MAY be registered		that apply to the link set document. Profile URIs MAY be registered
	in the IANA Profile URI Registry in the manner specified by		in the IANA's "Profile URIs" registry in the manner specified by
	[RFC7284]. Section 7.4.1 shows an example of using the "profile"		[RFC7284]. Section 7.4.1 shows an example of using the "profile"
	attribute on a link with the "linkset" relation type, making both the		attribute on a link with the "linkset" relation type, making both the
	link set and the profile(s) to which it complies discoverable.		link set and the profile(s) to which it complies discoverable.
	7. Examples		7. Examples
	Section 7.1 and Section 7.2 show examples whereby a set of links is		Sections 7.1 and 7.2 show examples whereby a set of links is provided
	provided as "application/linkset" and "application/linkset+json"		as "application/linkset" and "application/linkset+json" documents,
	documents, respectively. Section 7.3 illustrates the use of the		respectively. Section 7.3 illustrates the use of the "linkset" link
	"linkset" link relation type to support discovery of sets of links		relation type to support the discovery of sets of links, and
	and Section 7.4 shows how to convey profile information pertaining to		Section 7.4 shows how to convey profile information pertaining to a
	a link set.		link set.
	7.1. Set of Links Provided as application/linkset		7.1. Set of Links Provided as "application/linkset"
	Figure 7 shows a client issuing an HTTP GET request against resource		Figure 7 shows a client issuing an HTTP GET request against resource
	<https://example.org/links/resource1>.		<https://example.org/links/resource1>.
	GET /links/resource1 HTTP/1.1		GET /links/resource1 HTTP/1.1
	Host: example.org		Host: example.org
	Figure 7: Client HTTP GET request		Figure 7: Client HTTP GET request
	Figure 8 shows the response to the GET request of Figure 7. The		Figure 8 shows the response to the GET request of Figure 7. The
	response contains a Content-Type header field specifying that the		response contains a "Content-Type" header field specifying that the
	media type of the response is "application/linkset". A set of links,		media type of the response is "application/linkset". A set of links,
	revealing authorship and versioning related to resource		revealing authorship and versioning related to resource
	<https://example.org/resource1>, is provided in the response body.		<https://example.org/resource1>, is provided in the response body.
	The HTTP "Link" header field indicates the availability of an		The HTTP "Link" header field indicates the availability of an
	alternate representation of the set of links using media type		alternate representation of the set of links using media type
	"application/linkset+json".		"application/linkset+json".
	HTTP/1.1 200 OK		HTTP/1.1 200 OK
	Date: Mon, 12 Aug 2019 10:35:51 GMT		Date: Mon, 12 Aug 2019 10:35:51 GMT
	Server: Apache-Coyote/1.1		Server: Apache-Coyote/1.1
	skipping to change at page 18, line 46 ¶		skipping to change at line 804 ¶
	; rel="memento"		; rel="memento"
	; type="text/html"		; type="text/html"
	; datetime="Sun, 21 Jul 2019 12:22:04 GMT"		; datetime="Sun, 21 Jul 2019 12:22:04 GMT"
	; anchor="https://example.org/resource1",		; anchor="https://example.org/resource1",
	<https://authors.example.net/alice>		<https://authors.example.net/alice>
	; rel="author"		; rel="author"
	; anchor="https://example.org/resource1#comment=1"		; anchor="https://example.org/resource1#comment=1"
	Figure 8: Response to HTTP GET includes a set of links		Figure 8: Response to HTTP GET includes a set of links
	7.2. Set of Links Provided as application/linkset+json		7.2. Set of Links Provided as "application/linkset+json"
	Figure 9 shows the client issuing an HTTP GET request against		Figure 9 shows the client issuing an HTTP GET request against
	<https://example.org/links/resource1>. In the request, the client		<https://example.org/links/resource1>. In the request, the client
	uses an "Accept" header field to indicate it prefers a response in		uses an "Accept" header field to indicate that it prefers a response
	the "application/linkset+json" format.		in the "application/linkset+json" format.
	GET links/resource1 HTTP/1.1		GET links/resource1 HTTP/1.1
	Host: example.org		Host: example.org
	Accept: application/linkset+json		Accept: application/linkset+json
	Figure 9: Client HTTP GET request expressing preference for		Figure 9: Client HTTP GET request expressing preference for an
	"application/ linkset+json" response		"application/linkset+json" response
	Figure 10 shows the response to the HTTP GET request of Figure 9.		Figure 10 shows the response to the HTTP GET request of Figure 9.
	The set of links is serialized according to the media type		The set of links is serialized according to the media type
	"application/linkset+json".		"application/linkset+json".
	HTTP/1.1 200 OK		HTTP/1.1 200 OK
	Date: Mon, 12 Aug 2019 10:46:22 GMT		Date: Mon, 12 Aug 2019 10:46:22 GMT
	Server: Apache-Coyote/1.1		Server: Apache-Coyote/1.1
	Content-Type: application/linkset+json		Content-Type: application/linkset+json
	Link: <https://example.org/links/resource1>		Link: <https://example.org/links/resource1>
	skipping to change at page 20, line 4 ¶		skipping to change at line 859 ¶
	"latest-version": [		"latest-version": [
	{ "href": "https://example.org/resource1?version=3",		{ "href": "https://example.org/resource1?version=3",
	"type": "text/html"		"type": "text/html"
	}		}
	]		]
	},		},
	{ "anchor": "https://example.org/resource1?version=3",		{ "anchor": "https://example.org/resource1?version=3",
	"predecessor-version": [		"predecessor-version": [
	{ "href": "https://example.org/resource1?version=2",		{ "href": "https://example.org/resource1?version=2",
	"type": "text/html"		"type": "text/html"
	}		}
	]		]
	},		},
	{ "anchor": "https://example.org/resource1?version=2",		{ "anchor": "https://example.org/resource1?version=2",
	"predecessor-version": [		"predecessor-version": [
	{ "href": "https://example.org/resource1?version=1",		{ "href": "https://example.org/resource1?version=1",
	"type": "text/html"		"type": "text/html"
	}		}
	]		]
	},		},
	{ "anchor": "https://example.org/resource1#comment=1",		{ "anchor": "https://example.org/resource1#comment=1",
	"author": [		"author": [
	{ "href": "https://authors.example.net/alice"}		{ "href": "https://authors.example.net/alice"}
	]		]
	}		}
	]		]
	}		}
	Figure 10: Response to the client's request for the set of links		Figure 10: Response to the client's request for the linkset
	7.3. Discovering a Link Set via the "linkset" Link Relation Type		7.3. Discovering a Link Set via the "linkset" Link Relation Type
	Figure 11 shows a client issuing an HTTP HEAD request against		Figure 11 shows a client issuing an HTTP HEAD request against
	resource <https://example.org/resource1>.		resource <https://example.org/resource1>.
	HEAD resource1 HTTP/1.1		HEAD resource1 HTTP/1.1
	Host: example.org		Host: example.org
	Figure 11: Client HTTP HEAD request		Figure 11: Client HTTP HEAD request
	skipping to change at page 21, line 25 ¶		skipping to change at line 926 ¶
	Figure 13 shows a client issuing an HTTP HEAD request against trade		Figure 13 shows a client issuing an HTTP HEAD request against trade
	item 09506000134352 at <https://id.gs1.org/01/9506000134352>.		item 09506000134352 at <https://id.gs1.org/01/9506000134352>.
	HEAD /01/9506000134352 HTTP/1.1		HEAD /01/9506000134352 HTTP/1.1
	Host: id.gs1.org		Host: id.gs1.org
	Figure 13: Client HTTP HEAD request		Figure 13: Client HTTP HEAD request
	Figure 14 shows the server's response to the request of Figure 13,		Figure 14 shows the server's response to the request of Figure 13,
	including a "linkset" link with a "profile" attribute that has the		including a "linkset" link with a "profile" attribute that has the
	Profile URI <https://www.gs1.org/voc/?show=linktypes> as its value.		profile URI <https://www.gs1.org/voc/?show=linktypes> as its value.
	Dereferencing that URI yields a profile document that lists all the		Dereferencing that URI yields a profile document that lists all the
	link relation types that a client can expect when requesting the link		link relation types that a client can expect when requesting the link
	set made discoverable by the "linkset" link. The link relation types		set made discoverable by the "linkset" link. The link relation types
	are presented in abbreviated form, e.g. <gs1:activityIdeas>, whereas		are presented in abbreviated form, e.g., <gs1:activityIdeas>, whereas
	the actual link relation type URIs are available as hyperlinks on the		the actual link relation type URIs are available as hyperlinks on the
	abbreviations, e.g. <https://www.gs1.org/voc/activityIdeas>. For		abbreviations, e.g., <https://www.gs1.org/voc/activityIdeas>. For
	posterity that profile document was saved in the Internet Archive at		posterity, that profile document was saved in the Internet Archive at
	<https://web.archive.org/web/20210927160406/https://www.gs1.org/		<https://web.archive.org/web/20210927160406/https://www.gs1.org/
	voc/?show=linktypes> on 27 September 2021.		voc/?show=linktypes> on 27 September 2021.
	HTTP/1.1 307 Temporary Redirect		HTTP/1.1 307 Temporary Redirect
	Date: Mon, 27 Sep 2021 16:03:07 GMT		Date: Mon, 27 Sep 2021 16:03:07 GMT
	Server: nginx		Server: nginx
	Link: https://id.gs1.org/01/9506000134352?linkType=all		Link: <https://id.gs1.org/01/9506000134352?linkType=all>
	; rel="linkset"		; rel="linkset"
	; type="application/linkset+json"		; type="application/linkset+json"
	; profile="https://www.gs1.org/voc/?show=linktypes"		; profile="https://www.gs1.org/voc/?show=linktypes"
	Location: https://example.com/risotto-rice-with-mushrooms/		Location: https://example.com/risotto-rice-with-mushrooms/
	Figure 14: Response to the client's HEAD request including a		Figure 14: Response to the client's HEAD request, including a
	"profile" attribute for the "linkset" link		"profile" attribute for the "linkset" link
	7.4.2. Using a "profile" Parameter with a Link Set Media Type		7.4.2. Using a "profile" Parameter with a Link Set Media Type
	Figure 15 shows a client issuing an HTTP HEAD request against the		Figure 15 shows a client issuing an HTTP HEAD request against the
	link set <https://id.gs1.org/01/9506000134352?linkType=all> that was		link set <https://id.gs1.org/01/9506000134352?linkType=all> that was
	discovered through the HTTP interactions shown in Section 7.4.1.		discovered through the HTTP interactions shown in Section 7.4.1.
	HEAD /01/9506000134352?linkType=all HTTP/1.1		HEAD /01/9506000134352?linkType=all HTTP/1.1
	Host: id.gs1.org		Host: id.gs1.org
	Figure 15: Client HTTP HEAD request		Figure 15: Client HTTP HEAD request
	Figure 16 shows the server's response to the request of Figure 15.		Figure 16 shows the server's response to the request of Figure 15.
	Note the "profile" parameter for the application/linkset+json media		Note the "profile" parameter for the "application/linkset+json" media
	type, which has as value the same Profile URI <https://www.gs1.org/		type, which has as its value the same profile URI
	voc/?show=linktypes> as was used in <xref target="Response_pr_at"/>.		<https://www.gs1.org/voc/?show=linktypes> as was used in Figure 14.
	HTTP/1.1 200 OK		HTTP/1.1 200 OK
	Date: Mon, 27 Sep 2021 16:03:33 GMT		Date: Mon, 27 Sep 2021 16:03:33 GMT
	Server: nginx		Server: nginx
	Content-Type: application/linkset+json;		Content-Type: application/linkset+json;
	profile="https://www.gs1.org/voc/?show=linktypes"		profile="https://www.gs1.org/voc/?show=linktypes"
	Content-Length: 396		Content-Length: 396
	Figure 16: Response to the client's HEAD request including a		Figure 16: Response to the client's HEAD request, including a
	"profile" parameter for the "application/linkset+json" media type		"profile" parameter for the "application/linkset+json" media type
	7.4.3. Using a Link with a "profile" Link Relation Type		7.4.3. Using a Link with a "profile" Link Relation Type
	Note that the response Figure 16 from the link set resource is		Note that the response shown in Figure 16 from the link set resource
	equivalent to the response shown in Figure 17, which leverages the		is equivalent to the response shown in Figure 17, which leverages the
	"profile" link relation type defined in [RFC6906].		"profile" link relation type defined in [RFC6906].
	HTTP/1.1 200 OK		HTTP/1.1 200 OK
	Date: Mon, 27 Sep 2021 16:03:33 GMT		Date: Mon, 27 Sep 2021 16:03:33 GMT
	Server: nginx		Server: nginx
	Content-Type: application/linkset+json		Content-Type: application/linkset+json
	Link: https://www.gs1.org/voc/?show=linktypes; rel="profile"		Link: <https://www.gs1.org/voc/?show=linktypes>; rel="profile"
	Content-Length: 396		Content-Length: 396
	Figure 17: Response to the client's HEAD request including a		Figure 17: Response to the client's HEAD request, including a
	"profile" link		"profile" link
	A link with a "profile" link relation type as shown in Figure 17 can		A link with a "profile" link relation type as shown in Figure 17 can
	also be conveyed in the link set document itself. This is		also be conveyed in the link set document itself. This is
	illustrated by Figure 18. Following the recommendation that all		illustrated by Figure 18. Following the recommendation that all
	links in a link set document should have an explicit anchor, such a		links in a link set document should have an explicit anchor, such a
	link has the URI of the link set itself as anchor and the Profile URI		link has the URI of the link set itself as the anchor and the profile
	as target. Multiple Profile URIs are handled by using multiple		URI as the target. Multiple profile URIs are handled by using
	"href" members.		multiple "href" members.
	{ "linkset":		{ "linkset":
	[		[
	{ "anchor": "https://id.gs1.org/01/9506000134352?linkType=all",		{ "anchor": "https://id.gs1.org/01/9506000134352?linkType=all",
	"profile": [		"profile": [
	{"href": "https://www.gs1.org/voc/?show=linktypes"}		{"href": "https://www.gs1.org/voc/?show=linktypes"}
	]		]
	},		},
	{ "anchor": "https://id.gs1.org/01/9506000134352",		{ "anchor": "https://id.gs1.org/01/9506000134352",
	"https://gs1.org/voc/whatsInTheBox": [		"https://gs1.org/voc/whatsInTheBox": [
	{"href": "https://example.com/en/packContents/GB"}		{"href": "https://example.com/en/packContents/GB"}
	]		]
	}		}
	]		]
	}		}
	Figure 18: A Link Set that declares the profile it complies with		Figure 18: A linkset that declares the profile it complies with,
	using a "profile" link		using a "profile" link
	8. IANA Considerations		8. IANA Considerations
	8.1. Link Relation Type: linkset		8.1. Link Relation Type: linkset
	The link relation type below should be registered by IANA in the Link		The link relation type below has been registered by IANA in the "Link
	Relation Type Registry as per Section 4.2 of Web Linking [RFC8288]:		Relation Types" registry as per Section 4.2 of [RFC8288]:
	Relation Name: linkset		Relation Name: linkset
	Description: The link target of a link with the "linkset" relation		Description: The link target of a link with the "linkset" relation
	type provides a set of links, including links in which the link		type provides a set of links, including links in which the link
	context of the link participates.		context of the link participates.
	Reference: [[ This document ]]		Reference: RFC 9264
	8.2. Media Type: application/linkset		8.2. Media Type: application/linkset
	The Internet media type application/linkset for a linkset encoded as		The Internet media type "application/linkset" for a linkset encoded
	described in Section 4.1 should be registered by IANA in the Media		as described in Section 4.1 has been registered by IANA in the "Media
	Type Registry as per [RFC6838].		Types" registry as per [RFC6838].
	Type name: application
	Subtype name: linkset		Type name: application
	Required parameters: N/A		Subtype name: linkset
	Optional parameters: profile		Required parameters: N/A
	Encoding considerations: Linksets are encoded according to the
	definition of [RFC8288]. The encoding of [RFC8288] is based on
	the general encoding rules of [I-D.ietf-httpbis-semantics], with
	the addition of allowing indicating character encoding and
	language for specific parameters as defined by [RFC8187].
	Security considerations: The security considerations of [[ This		Optional parameters: profile
	document ]] apply.
	Interoperability considerations: N/A		Encoding considerations: Linksets are encoded according to the
			definitions provided in [RFC8288]. The encoding discussed in
			[RFC8288] is based on the general encoding rules specified by HTTP
			[RFC9110] and allows specific parameters to be extended by the
			indication of character encoding and language as defined by
			[RFC8187].
	Published specification: [[ This document ]]		Security considerations: The security considerations of RFC 9264
			apply.
	Applications that use this media type: This media type is not		Interoperability considerations: N/A
	specific to any application, as it can be used by any application
	that wants to interchange web links.
	Additional information:		Published specification: RFC 9264
	Magic number(s): N/A		Applications that use this media type: This media type is not
			specific to any application, as it can be used by any application
			that wants to interchange Web Links.
	File extension(s): This media type does not propose a specific		Additional information:
			Magic number(s): N/A
			File extension(s): This media type does not propose a specific
	extension.		extension.
			Macintosh file type code(s): TEXT
	Macintosh file type code(s): TEXT		Person & email address to contact for further information: Erik
	Person & email address to contact for further information: Erik
	Wilde <erik.wilde@dret.net>		Wilde <erik.wilde@dret.net>
	Intended usage: COMMON		Intended usage: COMMON
	Restrictions on usage: none		Restrictions on usage: none
	Author: Erik Wilde <erik.wilde@dret.net>		Author: Erik Wilde <erik.wilde@dret.net>
	Change controller: IETF		Change controller: IETF
	8.3. Media Type: application/linkset+json		8.3. Media Type: application/linkset+json
	The Internet media type application/linkset+json for a linkset		The Internet media type "application/linkset+json" for a linkset
	encoded as described in Section 4.2 should be registered by IANA in		encoded as described in Section 4.2 has been registered by IANA in
	the Media Type Registry as per [RFC6838].		the "Media Types" registry as per [RFC6838].
	Type name: application
	Subtype name: linkset+json		Type name: application
	Required parameters: N/A		Subtype name: linkset+json
	Optional parameters: profile
	Encoding considerations: The encoding considerations of [RFC8259]		Required parameters: N/A
	apply
	Security considerations: The security considerations of [[ This		Optional parameters: profile
	document ]] apply.
	Interoperability considerations: The interoperability		Encoding considerations: The encoding considerations of [RFC8259]
	considerations of [RFC8259] apply.		apply.
	Published specification: [[ This document ]]		Security considerations: The security considerations of RFC 9264
			apply.
	Applications that use this media type: This media type is not		Interoperability considerations: The interoperability considerations
	specific to any application, as it can be used by any application		of [RFC8259] apply.
	that wants to interchange web links.
	Additional information:		Published specification: RFC 9264
	Magic number(s): N/A		Applications that use this media type: This media type is not
			specific to any application, as it can be used by any application
			that wants to interchange Web Links.
	File extension(s): JSON documents often use ".json" as the file		Additional information:
			Magic number(s): N/A
			File extension(s): JSON documents often use ".json" as the file
	extension, and this media type does not propose a specific		extension, and this media type does not propose a specific
	extension other than this generic one.		extension other than this generic one.
			Macintosh file type code(s): TEXT
	Macintosh file type code(s): TEXT		Person & email address to contact for further information: Erik
	Person & email address to contact for further information: Erik
	Wilde <erik.wilde@dret.net>		Wilde <erik.wilde@dret.net>
	Intended usage: COMMON		Intended usage: COMMON
	Restrictions on usage: none		Restrictions on usage: none
	Author: Erik Wilde <erik.wilde@dret.net>		Author: Erik Wilde <erik.wilde@dret.net>
	Change controller: IETF		Change controller: IETF
	9. Security Considerations		9. Security Considerations
	The security considerations of Section 7 of [RFC3986] apply, as well		The security considerations of Section 7 of [RFC3986] apply, as well
	as those of Web Linking [RFC8288] as long as the latter are not		as those of Web Linking [RFC8288] as long as the latter are not
	specifically discussing the risks of exposing information in HTTP		specifically discussing the risks of exposing information in HTTP
	header fields.		header fields.
	In general, links may cause information leakage when they expose		In general, links may cause information leakage when they expose
	information (such as URIs) that can be sensitive or private. Links		information (such as URIs) that can be sensitive or private. Links
	may expose "hidden URIs" that are not supposed to be openly shared,		may expose "hidden URIs" that are not supposed to be openly shared
	and may not be sufficiently protected. Ideally, none of the URIs		and that may not be sufficiently protected. Ideally, none of the
	exposed in links should be supposed to be "hidden"; instead, if these		URIs exposed in links should be supposed to be "hidden"; instead, if
	URIs are supposed to be limited to certain users, then technical		these URIs are supposed to be limited to certain users, then
	measures should be put in place so that accidentally exposing them		technical measures should be put in place so that accidentally
	does not cause any harm.		exposing them does not cause any harm.
	For the specific mechanisms defined in this specification, two		For the specific mechanisms defined in this specification, two
	security considerations should be taken into account:		security considerations should be taken into account:
	* The Web Linking model always has an "implicit context", which is		* The Web Linking model always has an "implicit context", which is
	the resource of the HTTP interaction. This original context can		the resource of the HTTP interaction. This original context can
	be lost or can change when self-contained link representations are		be lost or can change when self-contained link representations are
	moved. Changing the context can change the interpretation of		moved. Changing the context can change the interpretation of
	links when they have no explicit anchor, or when they use relative		links when they have no explicit anchor or when they use relative
	URIs. Applications may choose to ignore links that have no		URIs. Applications may choose to ignore links that have no
	explicit anchor or that use relative URIs when these are exchanged		explicit anchor or that use relative URIs when these are exchanged
	in stand-alone resources.		in standalone resources.
	* The model introduced in this specification supports "3rd party		* The model introduced in this specification supports "third-party
	links", where one party can provide links that have another		links", where one party can provide links that have another
	party's resource as an anchor. Depending on the link semantics		party's resource as an anchor. Depending on the link semantics
	and the application context, it is important to verify that there		and the application context, it is important to verify that there
	is sufficient trust in that 3rd party to allow it to provide these		is sufficient trust in that third party to allow it to provide
	links. Applications may choose to treat 3rd party links		these links. Applications may choose to treat third-party links
	differently than cases where a resource and the links for that		differently than cases where a resource and the links for that
	resource are provided by the same party.		resource are provided by the same party.
	10. Normative References		10. References
			10.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform		[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
	Resource Identifier (URI): Generic Syntax", STD 66,		Resource Identifier (URI): Generic Syntax", STD 66,
	RFC 3986, DOI 10.17487/RFC3986, January 2005,		RFC 3986, DOI 10.17487/RFC3986, January 2005,
	<https://www.rfc-editor.org/info/rfc3986>.		<https://www.rfc-editor.org/info/rfc3986>.
	[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax		[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
	Specifications: ABNF", STD 68, RFC 5234,		Specifications: ABNF", STD 68, RFC 5234,
	DOI 10.17487/RFC5234, January 2008,		DOI 10.17487/RFC5234, January 2008,
	<https://www.rfc-editor.org/info/rfc5234>.		<https://www.rfc-editor.org/info/rfc5234>.
	[RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying		[RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
	Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,		Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
	September 2009, <https://www.rfc-editor.org/info/rfc5646>.		September 2009, <https://www.rfc-editor.org/info/rfc5646>.
	[W3C.REC-json-ld-20140116]
	Sporny, M., Kellogg, G., and M. Lanthaler, "JSON-LD 1.0",
	World Wide Web Consortium Recommendation REC-json-ld-
	20140116, 16 January 2014,
	<https://www.w3.org/TR/2014/REC-json-ld-20140116>.
	[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type		[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
	Specifications and Registration Procedures", BCP 13,		Specifications and Registration Procedures", BCP 13,
	RFC 6838, DOI 10.17487/RFC6838, January 2013,		RFC 6838, DOI 10.17487/RFC6838, January 2013,
	<https://www.rfc-editor.org/info/rfc6838>.		<https://www.rfc-editor.org/info/rfc6838>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	[RFC8187] Reschke, J., "Indicating Character Encoding and Language		[RFC8187] Reschke, J., "Indicating Character Encoding and Language
	skipping to change at page 27, line 34 ¶		skipping to change at line 1211 ¶
	[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data		[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
	Interchange Format", STD 90, RFC 8259,		Interchange Format", STD 90, RFC 8259,
	DOI 10.17487/RFC8259, December 2017,		DOI 10.17487/RFC8259, December 2017,
	<https://www.rfc-editor.org/info/rfc8259>.		<https://www.rfc-editor.org/info/rfc8259>.
	[RFC8288] Nottingham, M., "Web Linking", RFC 8288,		[RFC8288] Nottingham, M., "Web Linking", RFC 8288,
	DOI 10.17487/RFC8288, October 2017,		DOI 10.17487/RFC8288, October 2017,
	<https://www.rfc-editor.org/info/rfc8288>.		<https://www.rfc-editor.org/info/rfc8288>.
	[I-D.ietf-httpbis-semantics]		[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
	Fielding, R. T., Nottingham, M., and J. Reschke, "HTTP		Ed., "HTTP Semantics", STD 97, RFC 9110,
	Semantics", Work in Progress, Internet-Draft, draft-ietf-		DOI 10.17487/RFC9110, June 2022,
	httpbis-semantics-19, 12 September 2021,		<https://www.rfc-editor.org/info/rfc9110>.
	<https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-
	semantics-19>.
	11. Informative References		[W3C.REC-json-ld]
			Sporny, M., Ed., Kellogg, G., Ed., and M. Lanthaler, Ed.,
			"JSON-LD 1.1: A JSON-based Serialization for Linked Data",
			W3C Recommendation REC-json-ld-20140116, July 2020,
			<https://www.w3.org/TR/json-ld/>.
	[W3C.REC-rdf11-concepts-20140225]		10.2. Informative References
	Cyganiak, R., Wood, D., and M. Lanthaler, "RDF 1.1
	Concepts and Abstract Syntax", World Wide Web Consortium		[DCMI-TERMS]
	Recommendation REC-rdf11-concepts-20140225, 25 February		Dublin Core Metadata Initiative, "DCMI Metadata Terms",
	2014,		January 2020, <https://www.dublincore.org/specifications/
	<https://www.w3.org/TR/2014/REC-rdf11-concepts-20140225>.		dublin-core/dcmi-terms/>.
	[RFC5988] Nottingham, M., "Web Linking", RFC 5988,		[RFC5988] Nottingham, M., "Web Linking", RFC 5988,
	DOI 10.17487/RFC5988, October 2010,		DOI 10.17487/RFC5988, October 2010,
	<https://www.rfc-editor.org/info/rfc5988>.		<https://www.rfc-editor.org/info/rfc5988>.
	[RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link		[RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link
	Format", RFC 6690, DOI 10.17487/RFC6690, August 2012,		Format", RFC 6690, DOI 10.17487/RFC6690, August 2012,
	<https://www.rfc-editor.org/info/rfc6690>.		<https://www.rfc-editor.org/info/rfc6690>.
	[RFC6906] Wilde, E., "The 'profile' Link Relation Type", RFC 6906,		[RFC6906] Wilde, E., "The 'profile' Link Relation Type", RFC 6906,
	DOI 10.17487/RFC6906, March 2013,		DOI 10.17487/RFC6906, March 2013,
	<https://www.rfc-editor.org/info/rfc6906>.		<https://www.rfc-editor.org/info/rfc6906>.
	[RFC7284] Lanthaler, M., "The Profile URI Registry", RFC 7284,		[RFC7284] Lanthaler, M., "The Profile URI Registry", RFC 7284,
	DOI 10.17487/RFC7284, June 2014,		DOI 10.17487/RFC7284, June 2014,
	<https://www.rfc-editor.org/info/rfc7284>.		<https://www.rfc-editor.org/info/rfc7284>.
	[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running		[W3C.REC-rdf11-concepts]
	Code: The Implementation Status Section", BCP 205,		Cyganiak, R., Ed., Wood, D., Ed., and M. Lanthaler, Ed.,
	RFC 7942, DOI 10.17487/RFC7942, July 2016,		"RDF 1.1 Concepts and Abstract Syntax", W3C Consortium
	<https://www.rfc-editor.org/info/rfc7942>.		Recommendation REC-rdf11-concepts, February 2014,
			<https://www.w3.org/TR/rdf11-concepts/>.
	[DCMI-TERMS]
	Initiative, D. C. M., "DCMI Metadata Terms", 2020,
	<https://www.dublincore.org/specifications/dublin-core/
	dcmi-terms/>.
	Appendix A. JSON-LD Context		Appendix A. JSON-LD Context
	A set of links rendered according to the JSON serialization defined		A set of links rendered according to the JSON serialization defined
	in Section 4.2 can be interpreted as RDF triples by adding a JSON-LD		in Section 4.2 can be interpreted as RDF triples by adding a JSON-LD
	context [W3C.REC-json-ld-20140116] that maps the JSON keys to		context [W3C.REC-json-ld] that maps the JSON keys to corresponding
	corresponding Linked Data terms. And, as per		Linked Data terms. And, as per Section 6.1 of [W3C.REC-json-ld],
	[W3C.REC-json-ld-20140116] section 6.8 (https://www.w3.org/TR/2014/		when delivering a link set that is rendered according to the
	REC-json-ld-20140116/#interpreting-json-as-json-ld), when delivering		"application/linkset+json" media type to a user agent, a server can
	a link set that is rendered according to the "application/		convey the availability of such a JSON-LD context by using a link
	linkset+json" media type to a user agent, a server can convey the		with the relation type "http://www.w3.org/ns/json-ld#context" in the
	availability of such a JSON-LD context by using a link with the		HTTP "Link" header field.
	relation type "http://www.w3.org/ns/json-ld#context" in the HTTP
	"Link" header.
	Figure 19 shows the response to an HTTP GET against the URI of a link		Figure 19 shows the response to an HTTP GET against the URI of a link
	set resource and illustrates this approach to support discovery of a		set resource and illustrates this approach to support the discovery
	JSON-LD Context. The example is inspired by the GS1 implementation		of a JSON-LD context. This example is inspired by the GS1
	and shows a link set that uses relation types from the GS1 vocabulary		implementation and shows a link set that uses relation types from the
	at <https://www.gs1.org/voc/> that are expressed as HTTP URIs.		GS1 vocabulary at <https://www.gs1.org/voc/> that are expressed as
			HTTP URIs.
	HTTP/1.1 200 OK		HTTP/1.1 200 OK
	Date: Mon, 11 Oct 2021 10:48:22 GMT		Date: Mon, 11 Oct 2021 10:48:22 GMT
	Server: Apache-Coyote/1.1		Server: Apache-Coyote/1.1
	Content-Type: application/linkset+json		Content-Type: application/linkset+json
	Link: <https://example.org/contexts/linkset.jsonld>		Link: <https://example.org/contexts/linkset.jsonld>
	; rel="http://www.w3.org/ns/json-ld#context"		; rel="http://www.w3.org/ns/json-ld#context"
	; type="application/ld+json"		; type="application/ld+json"
	Content-Length: 1532		Content-Length: 1532
	skipping to change at page 30, line 26 ¶		skipping to change at line 1346 ¶
	"value": "Voyez-le en action!",		"value": "Voyez-le en action!",
	"language": "fr"		"language": "fr"
	}		}
	]		]
	}		}
	]		]
	}		}
	]		]
	}		}
	Figure 19: Using a typed link to support discovery of a JSON-LD		Figure 19: Using a typed link to support the discovery of a JSON-
	Context for a Set of Links		LD context for a linkset
	In order to obtain the JSON-LD Context conveyed by the server, the		In order to obtain the JSON-LD context conveyed by the server, the
	user agent issues an HTTP GET against the link target of the link		user agent issues an HTTP GET against the link target of the link
	with the "http://www.w3.org/ns/json-ld#context" relation type. The		with the "http://www.w3.org/ns/json-ld#context" relation type. The
	response to this GET is shown in Figure 20. This particular JSON-LD		response to this GET is shown in Figure 20. This particular JSON-LD
	context maps "application/linkset+json" representations of link sets		context maps "application/linkset+json" representations of link sets
	to Dublin Core Terms [DCMI-TERMS]. Note that the "linkset" entry in		to Dublin Core terms [DCMI-TERMS]. Note that the "linkset" entry in
	the JSON-LD context is introduced to support links with the "linkset"		the JSON-LD context is introduced to support links with the "linkset"
	relation type in link sets.		relation type in link sets.
	HTTP/1.1 200 OK		HTTP/1.1 200 OK
	Content-Type: application/ld+json		Content-Type: application/ld+json
	Content-Length: 658		Content-Length: 658
	{		{
	"@context": [		"@context": [
	{		{
	skipping to change at page 31, line 43 ¶		skipping to change at line 1396 ¶
	"language": "@language",		"language": "@language",
	"value": "@value",		"value": "@value",
	"hreflang": {		"hreflang": {
	"@id": "http://purl.org/dc/terms/language",		"@id": "http://purl.org/dc/terms/language",
	"@container": "@set"		"@container": "@set"
	}		}
	}		}
	]		]
	}		}
	Figure 20: JSON-LD Context mapping to Dublin Core Terms		Figure 20: JSON-LD context mapping to Dublin Core terms
	Applying the JSON-LD context of Figure 20 to the link set of		Applying the JSON-LD context of Figure 20 to the link set of
	Figure 19 allows transforming the "application/linkset+json" link set		Figure 19 allows transforming the "application/linkset+json" link set
	to an RDF link set. Figure 21 shows the latter represented by means		to an RDF link set. Figure 21 shows the latter represented by means
	of the "text/turtle" RDF serialization.		of the "text/turtle" RDF serialization.
	<https://example.com/en/defaultPage>		<https://example.com/en/defaultPage>
	<http://purl.org/dc/terms/format>		<http://purl.org/dc/terms/format>
	"text/html" .		"text/html" .
	<https://example.com/en/defaultPage>		<https://example.com/en/defaultPage>
	skipping to change at page 33, line 4 ¶		skipping to change at line 1451 ¶
	<https://example.com/fr/defaultPage> .		<https://example.com/fr/defaultPage> .
	<https://id.gs1.org/01/09506000149301>		<https://id.gs1.org/01/09506000149301>
	<https://gs1.org/voc/relatedVideo>		<https://gs1.org/voc/relatedVideo>
	<https://video.example> .		<https://video.example> .
	<https://id.gs1.org/01/09506000149301>		<https://id.gs1.org/01/09506000149301>
	<https://gs1.org/voc/whatsInTheBox>		<https://gs1.org/voc/whatsInTheBox>
	<https://example.com/en/packContents/GB> .		<https://example.com/en/packContents/GB> .
	<https://id.gs1.org/01/09506000149301>		<https://id.gs1.org/01/09506000149301>
	<https://gs1.org/voc/whatsInTheBox>		<https://gs1.org/voc/whatsInTheBox>
	<https://example.com/fr/packContents/CH> .		<https://example.com/fr/packContents/CH> .
	<https://id.gs1.org/01/09506000149301>		<https://id.gs1.org/01/09506000149301>
	<https://gs1.org/voc/whatsInTheBox>		<https://gs1.org/voc/whatsInTheBox>
	<https://example.com/fr/packContents/FR> .		<https://example.com/fr/packContents/FR> .
	<https://video.example>		<https://video.example>
	<http://purl.org/dc/terms/language>		<http://purl.org/dc/terms/language>
	"en" .		"en" .
	<https://video.example>		<https://video.example>
	<http://purl.org/dc/terms/language>		<http://purl.org/dc/terms/language>
	"fr" .		"fr" .
	<https://video.example>		<https://video.example>
	<http://purl.org/dc/terms/title>		<http://purl.org/dc/terms/title>
	"See it in action!"@en .		"See it in action!"@en .
	<https://video.example>		<https://video.example>
	<http://purl.org/dc/terms/title>		<http://purl.org/dc/terms/title>
	"Voyez-le en action!"@fr .		"Voyez-le en action!"@fr .
	Figure 21: RDF serialization of the link set resulting from		Figure 21: RDF serialization of the linkset resulting from
	applying the JSON-LD context		applying the JSON-LD context
	Appendix B. Implementation Status
	This section is to be removed before publishing as an RFC.
	This section records the status of known implementations of the
	protocol defined by this specification at the time of posting of this
	Internet-Draft, and is based on a proposal described in RFC 7942
	[RFC7942]. The description of implementations in this section is
	intended to assist the IETF in its decision processes in progressing
	drafts to RFCs. Please note that the listing of any individual
	implementation here does not imply endorsement by the IETF.
	Furthermore, no effort has been spent to verify the information
	presented here that was supplied by IETF contributors. This is not
	intended as, and must not be construed to be, a catalog of available
	implementations or their features. Readers are advised to note that
	other implementations may exist.
	According to RFC 7942, "this will allow reviewers and working groups
	to assign due consideration to documents that have the benefit of
	running code, which may serve as evidence of valuable experimentation
	and feedback that have made the implemented protocols more mature.
	It is up to the individual working groups to use this information as
	they see fit".
	B.1. GS1
	GS1 is a provider of identifiers, most famously seen in EAN/UPC
	barcodes for retail and healthcare products, and manages an ecology
	of services and standards to leverage them at a global scale. GS1
	has indicated that it will fully implement this "linkset"
	specification as a means to allow requesting and representing links
	pertaining to products, shipments, assets and locations. The current
	GS1 Digital Link specification makes an informative reference to
	version 03 of the "linkset" I-D, mentions the formal adoption of that
	I-D by the IETF HTTPAPI Working Group, and indicates it being on
	track to achieve RFC status. The GS1 Digital Link specification
	adopts the JSON format specified by the I-D and mentions future plans
	to also support the Link header format as well as their respective
	media types, neither of which have changed since version 03.
	B.2. FAIR Signposting Profile
	The FAIR Signposting Profile is a community specification aimed at
	improving machine navigation of scholarly objects on the web through
	the use of typed web links pointing at e.g. web resources that are
	part of a specific object, persistent identifiers for the object and
	its authors, license information pertaining to the object. The
	specification encourages the use of Linksets and initial
	implementations are ongoing, for example, for the open source
	Dataverse data repository platform that was initiated by Harvard
	University and is meanwhile used by research institutions, worldwide.
	B.3. Open Journal Systems (OJS)
	Open Journal Systems (OJS) is an open-source software for the
	management of peer-reviewed academic journals, and is created by the
	Public Knowledge Project (PKP), released under the GNU General Public
	License. Open Journal Systems (OJS) is a journal management and
	publishing system that has been developed by PKP through its
	federally funded efforts to expand and improve access to research.
	The OJS platform has implemented "linkset" support as an alternative
	way to provide links when there are more than a configured limit
	(they consider using about 10 as a good default, for testing purpose
	it is currently set to 8).
	Acknowledgements		Acknowledgements
	Thanks for comments and suggestions provided by Phil Archer,		Thanks for comments and suggestions provided by Phil Archer,
	Dominique Guinard, Mark Nottingham, Julian Reschke, Rob Sanderson,		Dominique Guinard, Mark Nottingham, Julian Reschke, Rob Sanderson,
	Stian Soiland-Reyes, Sarven Capadisli, and Addison Phillips.		Stian Soiland-Reyes, Sarven Capadisli, and Addison Phillips.
	Authors' Addresses		Authors' Addresses
	Erik Wilde		Erik Wilde
	Axway		Axway
	Email: erik.wilde@dret.net		Email: erik.wilde@dret.net
	URI: http://dret.net/netdret/
	Herbert Van de Sompel		Herbert Van de Sompel
	Data Archiving and Networked Services		Data Archiving and Networked Services
	Email: herbert.van.de.sompel@dans.knaw.nl		Email: herbert.van.de.sompel@dans.knaw.nl
	URI: https://orcid.org/0000-0002-0715-6126		URI: https://orcid.org/0000-0002-0715-6126
End of changes. 158 change blocks.
	492 lines changed or deleted		402 lines changed or added
This html diff was produced by rfcdiff 1.48.