< draft-nottingham-rfc5988bis-02.txt   draft-nottingham-rfc5988bis-03.txt >
Network Working Group M. Nottingham Network Working Group M. Nottingham
Internet-Draft November 22, 2016 Internet-Draft November 25, 2016
Obsoletes: 5988 (if approved) Obsoletes: 5988 (if approved)
Intended status: Standards Track Intended status: Standards Track
Expires: May 26, 2017 Expires: May 29, 2017
Web Linking Web Linking
draft-nottingham-rfc5988bis-02 draft-nottingham-rfc5988bis-03
Abstract Abstract
This specification defines a way to indicate the relationships This specification defines a way to indicate the relationships
between resources on the Web ("links") and the type of those between resources on the Web ("links") and the type of those
relationships ("link relation types"). relationships ("link relation types").
It also defines the serialisation of such links in HTTP headers with It also defines the serialisation of such links in HTTP headers with
the Link header field. the Link header field.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 26, 2017. This Internet-Draft will expire on May 29, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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 Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . 3 2. Notational Conventions . . . . . . . . . . . . . . . . . . . 3
3. Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Link Relation Types . . . . . . . . . . . . . . . . . . . . . 5 4. Link Relation Types . . . . . . . . . . . . . . . . . . . . . 5
4.1. Registered Relation Types . . . . . . . . . . . . . . . . 5 4.1. Registered Relation Types . . . . . . . . . . . . . . . . 5
4.1.1. Registering Link Relation Types . . . . . . . . . . . 6 4.1.1. Registering Link Relation Types . . . . . . . . . . . 6
4.1.2. Registration Request Processing . . . . . . . . . . . 7
4.2. Extension Relation Types . . . . . . . . . . . . . . . . 7 4.2. Extension Relation Types . . . . . . . . . . . . . . . . 7
5. Target Attributes . . . . . . . . . . . . . . . . . . . . . . 7 5. Target Attributes . . . . . . . . . . . . . . . . . . . . . . 8
6. Link Serialisation in HTTP Headers . . . . . . . . . . . . . 8 6. Link Serialisation in HTTP Headers . . . . . . . . . . . . . 8
6.1. Link Target . . . . . . . . . . . . . . . . . . . . . . . 8 6.1. Link Target . . . . . . . . . . . . . . . . . . . . . . . 9
6.2. Link Context . . . . . . . . . . . . . . . . . . . . . . 8 6.2. Link Context . . . . . . . . . . . . . . . . . . . . . . 9
6.3. Relation Type . . . . . . . . . . . . . . . . . . . . . . 9 6.3. Relation Type . . . . . . . . . . . . . . . . . . . . . . 9
6.4. Target Attributes . . . . . . . . . . . . . . . . . . . . 9 6.4. Target Attributes . . . . . . . . . . . . . . . . . . . . 10
6.4.1. Serialisation-Defined Attributes . . . . . . . . . . 10 6.4.1. Serialisation-Defined Attributes . . . . . . . . . . 10
6.4.2. Extension Attributes . . . . . . . . . . . . . . . . 11 6.4.2. Extension Attributes . . . . . . . . . . . . . . . . 11
6.5. Examples . . . . . . . . . . . . . . . . . . . . . . . . 11 6.5. Examples . . . . . . . . . . . . . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7.1. Link HTTP Header Field Registration . . . . . . . . . . . 12 7.1. Link HTTP Header Field Registration . . . . . . . . . . . 13
7.2. Link Relation Type Registry . . . . . . . . . . . . . . . 12 7.2. Link Relation Type Registry . . . . . . . . . . . . . . . 13
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13 9. Internationalisation Considerations . . . . . . . . . . . . . 14
9. Internationalisation Considerations . . . . . . . . . . . . . 13
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
10.1. Normative References . . . . . . . . . . . . . . . . . . 14 10.1. Normative References . . . . . . . . . . . . . . . . . . 14
10.2. Informative References . . . . . . . . . . . . . . . . . 15 10.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Notes on Other Link Serialisations . . . . . . . . . 17 Appendix A. Notes on Other Link Serialisations . . . . . . . . . 17
A.1. Link Serialisation in HTML . . . . . . . . . . . . . . . 17 A.1. Link Serialisation in HTML . . . . . . . . . . . . . . . 17
A.2. Link Serialisation in Atom . . . . . . . . . . . . . . . 18 A.2. Link Serialisation in Atom . . . . . . . . . . . . . . . 18
Appendix B. Algorithm for Parsing Link Headers . . . . . . . . . 18 Appendix B. Algorithm for Parsing Link Headers . . . . . . . . . 18
Appendix C. Changes from RFC5988 . . . . . . . . . . . . . . . . 21 Appendix C. Changes from RFC5988 . . . . . . . . . . . . . . . . 21
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 22 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction 1. Introduction
This specification defines a way to indicate the relationships This specification defines a way to indicate the relationships
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scoped to those conformance targets. scoped to those conformance targets.
This document uses the Augmented Backus-Naur Form (ABNF) notation of This document uses the Augmented Backus-Naur Form (ABNF) notation of
[RFC7230], including the #rule, and explicitly includes the following [RFC7230], including the #rule, and explicitly includes the following
rules from it: quoted-string, token, SP (space), BWS (bad rules from it: quoted-string, token, SP (space), BWS (bad
whitespace), OWS (optional whitespace), RWS (required whitespace) whitespace), OWS (optional whitespace), RWS (required whitespace)
LOALPHA, DIGIT. LOALPHA, DIGIT.
Additionally, the following rules are included from [RFC3986]: URI Additionally, the following rules are included from [RFC3986]: URI
and URI-Reference; from [RFC6838]: type-name and subtype-name; from and URI-Reference; from [RFC6838]: type-name and subtype-name; from
[W3C.CR-css3-mediaqueries-20090915]: media_query_list; from [W3C.CR-css3-mediaqueries-20090915]: media_query_list; and from
[RFC5646]: Language-Tag; and from [I-D.ietf-httpbis-rfc5987bis], ext- [RFC5646]: Language-Tag..
value and parmname.
3. Links 3. Links
In this specification, a link is a typed connection between two In this specification, a link is a typed connection between two
resources, and is comprised of: resources, and is comprised of:
o A _link context_, o A _link context_,
o a _link relation type_ (Section 4), o a _link relation type_ (Section 4),
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This specification does not place restrictions on the cardinality of This specification does not place restrictions on the cardinality of
links; there can be multiple links to and from a particular target, links; there can be multiple links to and from a particular target,
and multiple links of the same or different types between a given and multiple links of the same or different types between a given
context and target. Likewise, the relative ordering of links in any context and target. Likewise, the relative ordering of links in any
particular serialisation, or between serialisations (e.g., the Link particular serialisation, or between serialisations (e.g., the Link
header field and in-content links) is not specified or significant in header field and in-content links) is not specified or significant in
this specification; applications that wish to consider ordering this specification; applications that wish to consider ordering
significant can do so. significant can do so.
Links are conveyed in _link serialisations_; they are the "bytes on Links are conveyed in _link serialisations_; they are the "bytes on
the wire", and can occur in various forms. This specification does the wire", and can occur in various forms. For example, Atom
not define a general syntax for links, nor does it mandate a specific [RFC4287] and HTML [W3C.REC-html5-20141028] both defined
context for any given link; it is expected that serialisations of serialisations of links into their respective formats, and Section 6
links will specify both aspects. One such serialisation is defines how to serialise links in HTTP header fields.
communication of links through HTTP headers, specified in Section 6.
This specification does not define a general syntax for links across
different serialisations, nor does it mandate a specific context for
any given link; it is expected that serialisations of links will
specify both aspects.
Finally, links are consumed by _link applications_. Generally, an Finally, links are consumed by _link applications_. Generally, an
application will define the link relation types it uses, along with application will define the link relation types it uses, along with
the serialisations that they might occur within. For example, the the serialisations that they might occur within. For example, the
application "Web browsing" looks for the "stylesheet" link relation application "Web browsing" looks for the "stylesheet" link relation
type in the HTML link serialisation. type in the HTML link serialisation, whereas the application
"AtomPub" uses the "edit" and "edit-media" link relations.
4. Link Relation Types 4. Link Relation Types
In the simplest case, a link relation type identifies the semantics In the simplest case, a link relation type identifies the semantics
of a link. For example, a link with the relation type "copyright" of a link. For example, a link with the relation type "copyright"
indicates that the resource identified by the link target is a indicates that the resource identified by the link target is a
statement of the copyright terms applying to the current link statement of the copyright terms applying to the current link
context. context.
Link relation types can also be used to indicate that the target Link relation types can also be used to indicate that the target
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Historically, registered relation types have been identified with a Historically, registered relation types have been identified with a
URI [RFC3986] by prefixing their names with an application-defined URI [RFC3986] by prefixing their names with an application-defined
base URI (e.g., see Appendix A.2). This practice is NOT RECOMMENDED, base URI (e.g., see Appendix A.2). This practice is NOT RECOMMENDED,
because the resulting strings will not be considered equivalent to because the resulting strings will not be considered equivalent to
the registered relation types by other processors. Applications that the registered relation types by other processors. Applications that
do use such URIs internally MUST NOT use them in link serialisations do use such URIs internally MUST NOT use them in link serialisations
that do not explicitly accommodate them. that do not explicitly accommodate them.
4.1.1. Registering Link Relation Types 4.1.1. Registering Link Relation Types
Relation types are registered on the advice of a Designated Expert Any party can request registration of a link relation type.
(appointed by the IESG or their delegate), with a Specification
Required (using terminology from [RFC5226]).
The Expert(s) will establish procedures for requesting registrations, Registration requests can be sent to the "link-relations@ietf.org"
and make them available from the registry page. mailing list. The Expert(s) MAY establish alternate means of
requesting registrations, which SHOULD be linked to from the registry
page.
Registration requests consist of at least the following information: Registration requests consist of at least the following information:
o Relation Name: o *Relation Name*: The name of the relation type
o Description: o *Description*: A short English description of the type's
semantics. It SHOULD be stated in terms of the relationship
between the link context and link target.
o Reference: o *Reference*: Reference to the document that specifies the link
relation type, preferably including a URI that can be used to
retrieve a copy of the document. An indication of the relevant
section(s) MAY also be included, but is not required.
The Expert(s) MAY define additional fields to be collected in the The Expert(s) MAY define additional fields to be collected in the
registry. registry.
General requirements for registered relation types are described in General requirements for registered relation types are described in
Section 4.1. Section 4.1.
See the registry for examples of the description field; generally, it
SHOULD identify the semantics in terms of the link's context and
target.
Registrations MUST reference a freely available, stable Registrations MUST reference a freely available, stable
specification. specification.
Note that relation types can be registered by third parties, if the Note that relation types can be registered by third parties
Expert(s) determine that an unregistered relation type is widely (including the Expert(s)), if the Expert(s) determine that an
deployed and not likely to be registered in a timely manner. unregistered relation type is widely deployed and not likely to be
registered in a timely manner.
Decisions (or lack thereof) made by the Expert(s) can be first 4.1.2. Registration Request Processing
appealed to Application Area Directors (contactable using app-
ads@tools.ietf.org email address or directly by looking up their Relation types are registered on the advice of a Designated Expert
email addresses on http://www.iesg.org/ website) and, if the (appointed by the IESG or their delegate), with a Specification
appellant is not satisfied with the response, to the full IESG (using Required (using terminology from [RFC5226]).
the iesg@iesg.org mailing list).
The goal of the registry is to reflect common use of HTTP on the
Internet. Therefore, the Expert(s) SHOULD be strongly biased towards
approving registrations, unless they are abusive, frivolous, not
likely to be used on the Internet, or actively harmful to the
Internet and/or the Web (not merely aesthetically displeasing, or
architecturally dubious).
The Expert(s) MUST clearly identify any issues which cause a
registration to be refused. Advice about the syntax or semantics of
a proposed link relation type can be given, but if it does not block
registration, this SHOULD be explicitly stated.
When a request is approved, the Expert(s) will inform IANA, and the
registration will be processed. The IESG is the final arbiter of any
objection.
4.2. Extension Relation Types 4.2. Extension Relation Types
Applications that don't wish to register a relation type can use an Applications that don't wish to register a relation type can use an
extension relation type, which is a URI [RFC3986] that uniquely extension relation type, which is a URI [RFC3986] that uniquely
identifies the relation type. Although the URI can point to a identifies the relation type. Although the URI can point to a
resource that contains a definition of the semantics of the relation resource that contains a definition of the semantics of the relation
type, clients SHOULD NOT automatically access that resource to avoid type, clients SHOULD NOT automatically access that resource to avoid
overburdening its server. overburdening its server.
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link or its target; for example, a media type hint. link or its target; for example, a media type hint.
This specification does not attempt to coordinate the name of target This specification does not attempt to coordinate the name of target
attributes, their cardinality or use; they are defined both by attributes, their cardinality or use; they are defined both by
individual link relations and by link serialisations. individual link relations and by link serialisations.
Serialisations SHOULD coordinate their target attributes to avoid Serialisations SHOULD coordinate their target attributes to avoid
conflicts in semantics or syntax. Relation types MAY define conflicts in semantics or syntax. Relation types MAY define
additional target attributes specific to them. additional target attributes specific to them.
The names of target attributes SHOULD conform to the parmname rule The names of target attributes SHOULD conform to the token rule, but
for portability across serializations, and MUST be compared in a SHOULD NOT include any of the characters "%", "'" or "*", for
case-insensitive fashion. portability across serializations, and MUST be compared in a case-
insensitive fashion.
Target attribute definitions SHOULD specify: Target attribute definitions SHOULD specify:
o Their serialisation into Unicode or a subset thereof, to maximise o Their serialisation into Unicode or a subset thereof, to maximise
their chances of portability across link serialisations. their chances of portability across link serialisations.
o The semantics and error handling of multiple occurrences of the o The semantics and error handling of multiple occurrences of the
attribute on a given link. attribute on a given link.
This specification does define target attributes for use in the Link This specification does define target attributes for use in the Link
HTTP header field in Section 6.4. HTTP header field in Section 6.4.
6. Link Serialisation in HTTP Headers 6. Link Serialisation in HTTP Headers
The Link header field provides a means for serialising one or more The Link header field provides a means for serialising one or more
links into HTTP headers. links into HTTP headers.
The ABNF for the field value is given below: The ABNF for the field value is given below:
Link = #link-value Link = #link-value
link-value = "<" URI-Reference ">" *( OWS ";" OWS link-param ) link-value = "<" URI-Reference ">" *( OWS ";" OWS link-param )
link-param = token BWS "=" BWS ( token / quoted-string ) link-param = token BWS "=" BWS ( token / quoted-string )
Note that any "link-param" can be generated with values using either Note that any "link-param" can be generated with values using either
the "token" or the "quoted-string" syntax, and therefore recipients the "token" or the "quoted-string" syntax, and therefore recipients
MUST be able to parse both forms. Individual "link-param"s specify MUST be able to parse both forms. Individual "link-param"s specify
their syntax in terms of the value after any necessary unquoting (as their syntax in terms of the value after any necessary unquoting (as
per [RFC7230], Section 3.2.6). per [RFC7230], Section 3.2.6).
This specification defines the link-params "rel", "anchor", "rev", This specification defines the link-params "rel", "anchor", "rev",
"hreflang", "media", "title", "title*", and "type"; see Section 6.2, "hreflang", "media", "title", "title*", and "type"; see Section 6.2,
Section 6.3 and Section 6.4. Section 6.3 and Section 6.4.
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a link from A to B with REL="X" expresses the same relationship as a a link from A to B with REL="X" expresses the same relationship as a
link from B to A with REV="X". "rev" is deprecated by this link from B to A with REV="X". "rev" is deprecated by this
specification because it often confuses authors and readers; in most specification because it often confuses authors and readers; in most
cases, using a separate relation type is preferable. cases, using a separate relation type is preferable.
The ABNF for the "rel" and "rev" parameters' values is: ~~~ abnf2616 The ABNF for the "rel" and "rev" parameters' values is: ~~~ abnf2616
relation-type _( 1_SP relation-type ) ~~~ relation-type _( 1_SP relation-type ) ~~~
where: where:
relation-type = reg-rel-type | ext-rel-type relation-type = reg-rel-type | ext-rel-type
reg-rel-type = LOALPHA *( LOALPHA | DIGIT | "." | "-" ) reg-rel-type = LOALPHA *( LOALPHA | DIGIT | "." | "-" )
ext-rel-type = URI ext-rel-type = URI
Note that extension relation types are REQUIRED to be absolute URIs Note that extension relation types are REQUIRED to be absolute URIs
in Link headers, and MUST be quoted if they contain a semicolon (";") in Link headers, and MUST be quoted if they contain a semicolon (";")
or comma (",") (as these characters are used as delimiters in the or comma (",") (as these characters are used as delimiters in the
header field itself). header field itself).
6.4. Target Attributes 6.4. Target Attributes
The Link header field defines several target attributes specific to The Link header field defines several target attributes specific to
this serialisation, and also allows extension target attributes. this serialisation, and also allows extension target attributes.
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both forms are present, they SHOULD be considered to be the same both forms are present, they SHOULD be considered to be the same
target attribute; processors SHOULD use the value of the name ending target attribute; processors SHOULD use the value of the name ending
in "_" (after [I-D.ietf-httpbis-rfc5987bis] decoding), but MAY fall in "_" (after [I-D.ietf-httpbis-rfc5987bis] decoding), but MAY fall
back to the other value if there is an error in decoding it, or if back to the other value if there is an error in decoding it, or if
they do not support decoding. they do not support decoding.
6.5. Examples 6.5. Examples
For example: For example:
Link: <http://example.com/TheBook/chapter2>; rel="previous"; Link: <http://example.com/TheBook/chapter2>; rel="previous";
title="previous chapter" title="previous chapter"
indicates that "chapter2" is previous to this resource in a logical indicates that "chapter2" is previous to this resource in a logical
navigation path. navigation path.
Similarly, Similarly,
Link: </>; rel="http://example.net/foo" Link: </>; rel="http://example.net/foo"
indicates that the root resource ("/") is related to this resource indicates that the root resource ("/") is related to this resource
with the extension relation type "http://example.net/foo". with the extension relation type "http://example.net/foo".
The example below shows an instance of the Link header field encoding The example below shows an instance of the Link header field encoding
multiple links, and also the use of RFC 5987 encoding to encode both multiple links, and also the use of RFC 5987 encoding to encode both
non-ASCII characters and language information. non-ASCII characters and language information.
Link: </TheBook/chapter2>; Link: </TheBook/chapter2>;
rel="previous"; title*=UTF-8'de'letztes%20Kapitel, rel="previous"; title*=UTF-8'de'letztes%20Kapitel,
</TheBook/chapter4>; </TheBook/chapter4>;
rel="next"; title*=UTF-8'de'n%c3%a4chstes%20Kapitel rel="next"; title*=UTF-8'de'n%c3%a4chstes%20Kapitel
Here, both links have titles encoded in UTF-8, use the German Here, both links have titles encoded in UTF-8, use the German
language ("de"), and the second link contains the Unicode code point language ("de"), and the second link contains the Unicode code point
U+00E4 ("LATIN SMALL LETTER A WITH DIAERESIS"). U+00E4 ("LATIN SMALL LETTER A WITH DIAERESIS").
Note that link-values can convey multiple links between the same link Note that link-values can convey multiple links between the same link
target and link context; for example: target and link context; for example:
Link: <http://example.org/>; Link: <http://example.org/>;
rel="start http://example.net/relation/other" rel="start http://example.net/relation/other"
Here, the link to "http://example.org/" has the registered relation Here, the link to "http://example.org/" has the registered relation
type "start" and the extension relation type type "start" and the extension relation type
"http://example.net/relation/other". "http://example.net/relation/other".
7. IANA Considerations 7. IANA Considerations
In addition to the actions below, IANA should terminate the Link In addition to the actions below, IANA should terminate the Link
Relation Application Data Registry, as it has not been used, and Relation Application Data Registry, as it has not been used, and
future use is not anticipated. future use is not anticipated.
7.1. Link HTTP Header Field Registration 7.1. Link HTTP Header Field Registration
This specification updates the Message Header registry entry for This specification updates the Message Header registry entry for
"Link" in HTTP [RFC3864] to refer to this document. "Link" in HTTP [RFC3864] to refer to this document.
Header field: Link Header field: Link
Applicable protocol: http Applicable protocol: http
Status: standard Status: standard
Author/change controller: Author/change controller:
IETF (iesg@ietf.org) IETF (iesg@ietf.org)
Internet Engineering Task Force Internet Engineering Task Force
Specification document(s): Specification document(s):
[RFC&rfc.number;] [RFC&rfc.number;]
7.2. Link Relation Type Registry 7.2. Link Relation Type Registry
This specification updates the registration procedures for the Link This specification updates the registration procedures for the Link
Relation Type registry; see Section 4.1.1. The Expert(s) and IANA Relation Type registry; see Section 4.1.1. The Expert(s) and IANA
will interact as outlined below. will interact as outlined below.
IANA will direct any incoming requests regarding the registry to the IANA will direct any incoming requests regarding the registry to this
processes established by the Expert(s); typically, this will mean document and, if defined, the processes established by the Expert(s);
referring them to the registry Web page. typically, this will mean referring them to the registry Web page.
The Expert(s) will provide registry data to IANA in an agreed form The Expert(s) will provide registry data to IANA in an agreed form
(e.g. a specific XML format). IANA will publish: (e.g. a specific XML format). IANA will publish:
o The raw registry data o The raw registry data
o The registry data, transformed into HTML o The registry data, transformed into HTML
o The registry data in any alternative formats provided by the o The registry data in any alternative formats provided by the
Expert(s) Expert(s)
Each published document will be at a URL agreed to by IANA and the Each published document will be at a URL agreed to by IANA and the
Expert(s), and IANA will set HTTP response headers on them as Expert(s), and IANA will set HTTP response headers on them as
(reasonably) requested by the Expert(s). (reasonably) requested by the Expert(s).
Additionally, the HTML generated by IANA will: Additionally, the HTML generated by IANA will:
o Take directions from the Expert(s) as to the content of the HTML o Take directions from the Expert(s) as to the content of the HTML
page's introductory text and markup page's introductory text
o Include a stable HTML fragment identifier for each registered link o Include a stable HTML fragment identifier for each registered
relation header field
All registry data documents MUST include Simplified BSD License text All registry data documents MUST include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions as described in Section 4.e of the Trust Legal Provisions
(<http://trustee.ietf.org/license-info>). (<http://trustee.ietf.org/license-info>).
8. Security Considerations 8. Security Considerations
The content of the Link header field is not secure, private or The content of the Link header field is not secure, private or
integrity-guaranteed, and due caution should be exercised when using integrity-guaranteed, and due caution should be exercised when using
it. Use of Transport Layer Security (TLS) with HTTP ([RFC2818] and it. Use of Transport Layer Security (TLS) with HTTP ([RFC2818] and
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10. References 10. References
10.1. Normative References 10.1. Normative References
[I-D.ietf-httpbis-rfc5987bis] [I-D.ietf-httpbis-rfc5987bis]
Reschke, J., "Indicating Character Encoding and Language Reschke, J., "Indicating Character Encoding and Language
for HTTP Header Field Parameters", draft-ietf-httpbis- for HTTP Header Field Parameters", draft-ietf-httpbis-
rfc5987bis-03 (work in progress), July 2016. rfc5987bis-03 (work in progress), July 2016.
[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/
DOI 10.17487/RFC2119, March 1997, RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864, Procedures for Message Header Fields", BCP 90, RFC 3864,
DOI 10.17487/RFC3864, September 2004, DOI 10.17487/RFC3864, September 2004,
<http://www.rfc-editor.org/info/rfc3864>. <http://www.rfc-editor.org/info/rfc3864>.
[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
RFC 3986, DOI 10.17487/RFC3986, January 2005, 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>. <http://www.rfc-editor.org/info/rfc3986>.
[RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource [RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource
Identifiers (IRIs)", RFC 3987, DOI 10.17487/RFC3987, Identifiers (IRIs)", RFC 3987, DOI 10.17487/RFC3987,
January 2005, <http://www.rfc-editor.org/info/rfc3987>. January 2005, <http://www.rfc-editor.org/info/rfc3987>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008, DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>. <http://www.rfc-editor.org/info/rfc5226>.
[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, <http://www.rfc-editor.org/info/rfc5646>. September 2009, <http://www.rfc-editor.org/info/rfc5646>.
[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
RFC 6838, DOI 10.17487/RFC6838, January 2013, 6838, DOI 10.17487/RFC6838, January 2013,
<http://www.rfc-editor.org/info/rfc6838>. <http://www.rfc-editor.org/info/rfc6838>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing", Protocol (HTTP/1.1): Message Syntax and Routing", RFC
RFC 7230, DOI 10.17487/RFC7230, June 2014, 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>. <http://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231, Protocol (HTTP/1.1): Semantics and Content", RFC 7231, DOI
DOI 10.17487/RFC7231, June 2014, 10.17487/RFC7231, June 2014,
<http://www.rfc-editor.org/info/rfc7231>. <http://www.rfc-editor.org/info/rfc7231>.
[W3C.CR-css3-mediaqueries-20090915] [W3C.CR-css3-mediaqueries-20090915]
Lie, H., Celik, T., Glazman, D., and A. Kesteren, "Media Lie, H., Celik, T., Glazman, D., and A. Kesteren, "Media
Queries", World Wide Web Consortium CR CR-css3- Queries", World Wide Web Consortium CR CR-css3-
mediaqueries-20090915, September 2009, mediaqueries-20090915, September 2009,
<http://www.w3.org/TR/2009/CR-css3-mediaqueries-20090915>. <http://www.w3.org/TR/2009/CR-css3-mediaqueries-20090915>.
10.2. Informative References 10.2. Informative References
[RFC2068] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., and T. [RFC2068] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., and T.
Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1",
RFC 2068, DOI 10.17487/RFC2068, January 1997, RFC 2068, DOI 10.17487/RFC2068, January 1997,
<http://www.rfc-editor.org/info/rfc2068>. <http://www.rfc-editor.org/info/rfc2068>.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, Transfer Protocol -- HTTP/1.1", RFC 2616, DOI 10.17487/
DOI 10.17487/RFC2616, June 1999, RFC2616, June 1999,
<http://www.rfc-editor.org/info/rfc2616>. <http://www.rfc-editor.org/info/rfc2616>.
[RFC2817] Khare, R. and S. Lawrence, "Upgrading to TLS Within [RFC2817] Khare, R. and S. Lawrence, "Upgrading to TLS Within
HTTP/1.1", RFC 2817, DOI 10.17487/RFC2817, May 2000, HTTP/1.1", RFC 2817, DOI 10.17487/RFC2817, May 2000,
<http://www.rfc-editor.org/info/rfc2817>. <http://www.rfc-editor.org/info/rfc2817>.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/
DOI 10.17487/RFC2818, May 2000, RFC2818, May 2000,
<http://www.rfc-editor.org/info/rfc2818>. <http://www.rfc-editor.org/info/rfc2818>.
[RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom [RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
Syndication Format", RFC 4287, DOI 10.17487/RFC4287, Syndication Format", RFC 4287, DOI 10.17487/RFC4287,
December 2005, <http://www.rfc-editor.org/info/rfc4287>. December 2005, <http://www.rfc-editor.org/info/rfc4287>.
[W3C.REC-html-rdfa-20150317] [W3C.REC-html-rdfa-20150317]
Sporny, M., "HTML+RDFa 1.1 - Second Edition", World Wide Sporny, M., "HTML+RDFa 1.1 - Second Edition", World Wide
Web Consortium Recommendation REC-html-rdfa-20150317, Web Consortium Recommendation REC-html-rdfa-20150317,
March 2015, March 2015,
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