draft-ietf-httpbis-cache-11.txt		draft-ietf-httpbis-cache-12.txt
	HTTP Working Group R. Fielding, Ed.		HTTP Working Group R. Fielding, Ed.
	Internet-Draft Adobe		Internet-Draft Adobe
	Obsoletes: 7234 (if approved) M. Nottingham, Ed.		Obsoletes: 7234 (if approved) M. Nottingham, Ed.
	Intended status: Standards Track Fastly		Intended status: Standards Track Fastly
	Expires: February 28, 2021 J. F. Reschke, Ed.		Expires: April 5, 2021 J. Reschke, Ed.
	greenbytes		greenbytes
	August 27, 2020		October 2, 2020
	HTTP Caching		HTTP Caching
	draft-ietf-httpbis-cache-11		draft-ietf-httpbis-cache-12
	Abstract		Abstract
	The Hypertext Transfer Protocol (HTTP) is a stateless application-		The Hypertext Transfer Protocol (HTTP) is a stateless application-
	level protocol for distributed, collaborative, hypertext information		level protocol for distributed, collaborative, hypertext information
	systems. This document defines HTTP caches and the associated header		systems. This document defines HTTP caches and the associated header
	fields that control cache behavior or indicate cacheable response		fields that control cache behavior or indicate cacheable response
	messages.		messages.
	This document obsoletes RFC 7234.		This document obsoletes RFC 7234.
	skipping to change at page 1, line 36 ¶		skipping to change at page 1, line 36 ¶
	This note is to be removed before publishing as an RFC.		This note is to be removed before publishing as an RFC.
	Discussion of this draft takes place on the HTTP working group		Discussion of this draft takes place on the HTTP working group
	mailing list (ietf-http-wg@w3.org), which is archived at		mailing list (ietf-http-wg@w3.org), which is archived at
	<https://lists.w3.org/Archives/Public/ietf-http-wg/>.		<https://lists.w3.org/Archives/Public/ietf-http-wg/>.
	Working Group information can be found at <https://httpwg.org/>;		Working Group information can be found at <https://httpwg.org/>;
	source code and issues list for this draft can be found at		source code and issues list for this draft can be found at
	<https://github.com/httpwg/http-core>.		<https://github.com/httpwg/http-core>.
	The changes in this draft are summarized in Appendix C.12.		The changes in this draft are summarized in Appendix C.13.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	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 https://datatracker.ietf.org/drafts/current/.		Drafts is at https://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 February 28, 2021.		This Internet-Draft will expire on April 5, 2021.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2020 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 (https://trustee.ietf.org/
	license-info) in effect on the date of publication of this document.		license-info) in effect on the date of publication of this document.
	Please review these documents carefully, as they describe your rights		Please review these documents carefully, as they describe your rights
	skipping to change at page 4, line 21 ¶		skipping to change at page 4, line 21 ¶
	C.3. Since draft-ietf-httpbis-cache-01 . . . . . . . . . . . . 39		C.3. Since draft-ietf-httpbis-cache-01 . . . . . . . . . . . . 39
	C.4. Since draft-ietf-httpbis-cache-02 . . . . . . . . . . . . 39		C.4. Since draft-ietf-httpbis-cache-02 . . . . . . . . . . . . 39
	C.5. Since draft-ietf-httpbis-cache-03 . . . . . . . . . . . . 39		C.5. Since draft-ietf-httpbis-cache-03 . . . . . . . . . . . . 39
	C.6. Since draft-ietf-httpbis-cache-04 . . . . . . . . . . . . 40		C.6. Since draft-ietf-httpbis-cache-04 . . . . . . . . . . . . 40
	C.7. Since draft-ietf-httpbis-cache-05 . . . . . . . . . . . . 40		C.7. Since draft-ietf-httpbis-cache-05 . . . . . . . . . . . . 40
	C.8. Since draft-ietf-httpbis-cache-06 . . . . . . . . . . . . 40		C.8. Since draft-ietf-httpbis-cache-06 . . . . . . . . . . . . 40
	C.9. Since draft-ietf-httpbis-cache-07 . . . . . . . . . . . . 41		C.9. Since draft-ietf-httpbis-cache-07 . . . . . . . . . . . . 41
	C.10. Since draft-ietf-httpbis-cache-08 . . . . . . . . . . . . 41		C.10. Since draft-ietf-httpbis-cache-08 . . . . . . . . . . . . 41
	C.11. Since draft-ietf-httpbis-cache-09 . . . . . . . . . . . . 41		C.11. Since draft-ietf-httpbis-cache-09 . . . . . . . . . . . . 41
	C.12. Since draft-ietf-httpbis-cache-10 . . . . . . . . . . . . 41		C.12. Since draft-ietf-httpbis-cache-10 . . . . . . . . . . . . 41
			C.13. Since draft-ietf-httpbis-cache-11 . . . . . . . . . . . . 42
	Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 42		Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 42
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42
	1. Introduction		1. Introduction
	The Hypertext Transfer Protocol (HTTP) is a stateless application-		The Hypertext Transfer Protocol (HTTP) is a stateless application-
	level request/response protocol that uses extensible semantics and		level request/response protocol that uses extensible semantics and
	self-descriptive messages for flexible interaction with network-based		self-descriptive messages for flexible interaction with network-based
	hypertext information systems. HTTP is defined by a series of		hypertext information systems. HTTP is defined by a series of
	documents that collectively form the HTTP/1.1 specification:		documents that collectively form the HTTP/1.1 specification:
	skipping to change at page 5, line 32 ¶		skipping to change at page 5, line 32 ¶
	in Appendix B.		in Appendix B.
	1.1. Requirements Notation		1.1. Requirements Notation
	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 BCP
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	Section 3 of [Semantics] defines conformance criteria and contains		Section 2 of [Semantics] defines conformance criteria and contains
	considerations regarding error handling.		considerations regarding error handling.
	1.2. Syntax Notation		1.2. Syntax Notation
	This specification uses the Augmented Backus-Naur Form (ABNF)		This specification uses the Augmented Backus-Naur Form (ABNF)
	notation of [RFC5234], extended with the notation for case-		notation of [RFC5234], extended with the notation for case-
	sensitivity in strings defined in [RFC7405].		sensitivity in strings defined in [RFC7405].
	It also uses a list extension, defined in Section 5.5 of [Semantics],		It also uses a list extension, defined in Section 5.7.1 of
	that allows for compact definition of comma-separated lists using a		[Semantics], that allows for compact definition of comma-separated
	'#' operator (similar to how the '*' operator indicates repetition).		lists using a '#' operator (similar to how the '*' operator indicates
	Appendix A shows the collected grammar with all list operators		repetition). Appendix A shows the collected grammar with all list
	expanded to standard ABNF notation.		operators expanded to standard ABNF notation.
	The following core rules are included by reference, as defined in		The following core rules are included by reference, as defined in
	[RFC5234], Appendix B.1: ALPHA (letters), CR (carriage return), CRLF		[RFC5234], Appendix B.1: ALPHA (letters), CR (carriage return), CRLF
	(CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote),		(CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote),
	HEXDIG (hexadecimal 0-9/A-F/a-f), HTAB (horizontal tab), LF (line		HEXDIG (hexadecimal 0-9/A-F/a-f), HTAB (horizontal tab), LF (line
	feed), OCTET (any 8-bit sequence of data), SP (space), and VCHAR (any		feed), OCTET (any 8-bit sequence of data), SP (space), and VCHAR (any
	visible [USASCII] character).		visible [USASCII] character).
	[Semantics] defines the following rules:		[Semantics] defines the following rules:
	HTTP-date = <HTTP-date, see [Semantics], Section 5.4.1.5>		HTTP-date = <HTTP-date, see [Semantics], Section 5.7.7>
	OWS = <OWS, see [Semantics], Section 1.6.1>		OWS = <OWS, see [Semantics], Section 5.7.3>
	field-name = <field-name, see [Semantics], Section 5.3>		field-name = <field-name, see [Semantics], Section 5.4.3>
	quoted-string = <quoted-string, see [Semantics], Section 5.4.1.2>		quoted-string = <quoted-string, see [Semantics], Section 5.7.4>
	token = <token, see [Semantics], Section 5.4.1.1>		token = <token, see [Semantics], Section 5.7.2>
	1.3. Delta Seconds		1.3. Delta Seconds
	The delta-seconds rule specifies a non-negative integer, representing		The delta-seconds rule specifies a non-negative integer, representing
	time in seconds.		time in seconds.
	delta-seconds = 1*DIGIT		delta-seconds = 1*DIGIT
	A recipient parsing a delta-seconds value and converting it to binary		A recipient parsing a delta-seconds value and converting it to binary
	form ought to use an arithmetic type of at least 31 bits of non-		form ought to use an arithmetic type of at least 31 bits of non-
	skipping to change at page 7, line 41 ¶		skipping to change at page 7, line 41 ¶
	A cache is disconnected when it cannot contact the origin server or		A cache is disconnected when it cannot contact the origin server or
	otherwise find a forward path for a request. A disconnected cache		otherwise find a forward path for a request. A disconnected cache
	can serve stale responses in some circumstances (Section 4.2.4).		can serve stale responses in some circumstances (Section 4.2.4).
	3. Storing Responses in Caches		3. Storing Responses in Caches
	A cache MUST NOT store a response to a request unless:		A cache MUST NOT store a response to a request unless:
	o the request method is understood by the cache;		o the request method is understood by the cache;
	o the response status code is final (see Section 10 of [Semantics]);		o the response status code is final (see Section 14 of [Semantics]);
	o if the response status code is 206 or 304, or the "must-		o if the response status code is 206 or 304, or the "must-
	understand" cache directive (see Section 5.2) is present: the		understand" cache directive (see Section 5.2) is present: the
	cache understands the response status code;		cache understands the response status code;
	o the "no-store" cache directive is not present in the response (see		o the "no-store" cache directive is not present in the response (see
	Section 5.2);		Section 5.2);
	o if the cache is shared: the "private" response directive is either		o if the cache is shared: the "private" response directive is either
	not present or allows a shared cache to store a modified response;		not present or allows a shared cache to store a modified response;
	see Section 5.2.2.7);		see Section 5.2.2.7);
	o if the cache is shared: the Authorization header field is not		o if the cache is shared: the Authorization header field is not
	present in the request (see Section 9.5.3 of [Semantics]) or a		present in the request (see Section 10.6.2 of [Semantics]) or a
	response directive is present that explicitly allows shared		response directive is present that explicitly allows shared
	caching (see Section 3.3); and,		caching (see Section 3.3); and,
	o the response contains at least one of:		o the response contains at least one of:
	* a public response directive (see Section 5.2.2.6);		* a public response directive (see Section 5.2.2.6);
	* a private response directive, if the cache is not shared (see		* a private response directive, if the cache is not shared (see
	Section 5.2.2.7);		Section 5.2.2.7);
	skipping to change at page 9, line 12 ¶		skipping to change at page 9, line 12 ¶
	before forwarding the message. This MAY be implemented by doing		before forwarding the message. This MAY be implemented by doing
	so before storage.		so before storage.
	o Likewise, some fields' semantics require them to be removed before		o Likewise, some fields' semantics require them to be removed before
	forwarding the message, and this MAY be implemented by doing so		forwarding the message, and this MAY be implemented by doing so
	before storage; see Section 13.1 of [Messaging] for some examples.		before storage; see Section 13.1 of [Messaging] for some examples.
	o Header fields that are specific to a client's proxy configuration		o Header fields that are specific to a client's proxy configuration
	MUST NOT be stored, unless the cache incorporates the identity of		MUST NOT be stored, unless the cache incorporates the identity of
	the proxy into the cache key. Effectively, this is limited to		the proxy into the cache key. Effectively, this is limited to
	Proxy-Authenticate (Section 11.3.2 of [Semantics]), Proxy-		Proxy-Authenticate (Section 10.7.1 of [Semantics]), Proxy-
	Authentication-Info (Section 11.3.4 of [Semantics]), and Proxy-		Authentication-Info (Section 10.7.3 of [Semantics]), and Proxy-
	Authorization (Section 9.5.4 of [Semantics]).		Authorization (Section 10.7.2 of [Semantics]).
	Caches MAY either store trailer fields separate from header fields,		Caches MAY either store trailer fields separate from header fields,
	or discard them. Caches MUST NOT combine trailer fields with header		or discard them. Caches MUST NOT combine trailer fields with header
	fields.		fields.
	3.2. Storing Incomplete Responses		3.2. Storing Incomplete Responses
	If the request method is GET, the response status code is 200 (OK),		If the request method is GET, the response status code is 200 (OK),
	and the entire response header section has been received, a cache MAY		and the entire response header section has been received, a cache MAY
	store a response body that is not complete (Section 2.1 of		store a response body that is not complete (Section 3.3 of
	[Semantics]) if the stored response is recorded as being incomplete.		[Semantics]) if the stored response is recorded as being incomplete.
	Likewise, a 206 (Partial Content) response MAY be stored as if it		Likewise, a 206 (Partial Content) response MAY be stored as if it
	were an incomplete 200 (OK) response. However, a cache MUST NOT		were an incomplete 200 (OK) response. However, a cache MUST NOT
	store incomplete or partial-content responses if it does not support		store incomplete or partial-content responses if it does not support
	the Range and Content-Range header fields or if it does not		the Range and Content-Range header fields or if it does not
	understand the range units used in those fields.		understand the range units used in those fields.
	A cache MAY complete a stored incomplete response by making a		A cache MAY complete a stored incomplete response by making a
	subsequent range request (Section 9.3 of [Semantics]) and combining		subsequent range request (Section 13.2 of [Semantics]) and combining
	the successful response with the stored response, as defined in		the successful response with the stored response, as defined in
	Section 3.4. A cache MUST NOT use an incomplete response to answer		Section 3.4. A cache MUST NOT use an incomplete response to answer
	requests unless the response has been made complete, or the request		requests unless the response has been made complete, or the request
	is partial and specifies a range wholly within the incomplete		is partial and specifies a range wholly within the incomplete
	response. A cache MUST NOT send a partial response to a client		response. A cache MUST NOT send a partial response to a client
	without explicitly marking it using the 206 (Partial Content) status		without explicitly marking it using the 206 (Partial Content) status
	code.		code.
	3.3. Storing Responses to Authenticated Requests		3.3. Storing Responses to Authenticated Requests
	A shared cache MUST NOT use a cached response to a request with an		A shared cache MUST NOT use a cached response to a request with an
	Authorization header field (Section 9.5.3 of [Semantics]) to satisfy		Authorization header field (Section 10.6.2 of [Semantics]) to satisfy
	any subsequent request unless the response contains a Cache-Control		any subsequent request unless the response contains a Cache-Control
	field with a response directive (Section 5.2.2) that allows it to be		field with a response directive (Section 5.2.2) that allows it to be
	stored by a shared cache and the cache conforms to the requirements		stored by a shared cache and the cache conforms to the requirements
	of that directive for that response.		of that directive for that response.
	In this specification, the following response directives have such an		In this specification, the following response directives have such an
	effect: must-revalidate (Section 5.2.2.1), public (Section 5.2.2.6),		effect: must-revalidate (Section 5.2.2.1), public (Section 5.2.2.6),
	and s-maxage (Section 5.2.2.10).		and s-maxage (Section 5.2.2.10).
	3.4. Combining Partial Content		3.4. Combining Partial Content
	A response might transfer only a partial representation if the		A response might transfer only a partial representation if the
	connection closed prematurely or if the request used one or more		connection closed prematurely or if the request used one or more
	Range specifiers (Section 9.3 of [Semantics]). After several such		Range specifiers (Section 13.2 of [Semantics]). After several such
	transfers, a cache might have received several ranges of the same		transfers, a cache might have received several ranges of the same
	representation. A cache MAY combine these ranges into a single		representation. A cache MAY combine these ranges into a single
	stored response, and reuse that response to satisfy later requests,		stored response, and reuse that response to satisfy later requests,
	if they all share the same strong validator and the cache complies		if they all share the same strong validator and the cache complies
	with the client requirements in Section 10.3.7.3 of [Semantics].		with the client requirements in Section 14.3.7.3 of [Semantics].
	When combining the new response with one or more stored responses, a		When combining the new response with one or more stored responses, a
	cache MUST use the header fields provided in the new response, aside		cache MUST use the header fields provided in the new response, aside
	from Content-Range, to replace all instances of the corresponding		from Content-Range, to replace all instances of the corresponding
	header fields in the stored response.		header fields in the stored response.
	4. Constructing Responses from Caches		4. Constructing Responses from Caches
	When presented with a request, a cache MUST NOT reuse a stored		When presented with a request, a cache MUST NOT reuse a stored
	response, unless:		response, unless:
	skipping to change at page 11, line 29 ¶		skipping to change at page 11, line 29 ¶
	most recent one (as determined by the Date header field). It can		most recent one (as determined by the Date header field). It can
	also forward the request with "Cache-Control: max-age=0" or "Cache-		also forward the request with "Cache-Control: max-age=0" or "Cache-
	Control: no-cache" to disambiguate which response to use.		Control: no-cache" to disambiguate which response to use.
	A cache that does not have a clock available MUST NOT use stored		A cache that does not have a clock available MUST NOT use stored
	responses without revalidating them upon every use.		responses without revalidating them upon every use.
	4.1. Calculating Cache Keys with Vary		4.1. Calculating Cache Keys with Vary
	When a cache receives a request that can be satisfied by a stored		When a cache receives a request that can be satisfied by a stored
	response that has a Vary header field (Section 11.1.4 of		response that has a Vary header field (Section 11.2.1 of
	[Semantics]), it MUST NOT use that response unless all the selecting		[Semantics]), it MUST NOT use that response unless all the selecting
	header fields nominated by the Vary header field match in both the		header fields nominated by the Vary header field match in both the
	original request (i.e., that associated with the stored response),		original request (i.e., that associated with the stored response),
	and the presented request.		and the presented request.
	The selecting header fields from two requests are defined to match if		The selecting header fields from two requests are defined to match if
	and only if those in the first request can be transformed to those in		and only if those in the first request can be transformed to those in
	the second request by applying any of:		the second request by applying any of:
	o adding or removing whitespace, where allowed in the header field's		o adding or removing whitespace, where allowed in the header field's
	syntax		syntax
	o combining multiple header fields with the same field name (see		o combining multiple header fields with the same field name (see
	Section 5.4 of [Semantics])		Section 5.4.4 of [Semantics])
	o normalizing both header field values in a way that is known to		o normalizing both header field values in a way that is known to
	have identical semantics, according to the header field's		have identical semantics, according to the header field's
	specification (e.g., reordering field values when order is not		specification (e.g., reordering field values when order is not
	significant; case-normalization, where values are defined to be		significant; case-normalization, where values are defined to be
	case-insensitive)		case-insensitive)
	If (after any normalization that might take place) a header field is		If (after any normalization that might take place) a header field is
	absent from a request, it can only match another request if it is		absent from a request, it can only match another request if it is
	also absent there.		also absent there.
	skipping to change at page 15, line 9 ¶		skipping to change at page 15, line 9 ¶
	a cache MAY assign a heuristic expiration time when an explicit time		a cache MAY assign a heuristic expiration time when an explicit time
	is not specified, employing algorithms that use other header field		is not specified, employing algorithms that use other header field
	values (such as the Last-Modified time) to estimate a plausible		values (such as the Last-Modified time) to estimate a plausible
	expiration time. This specification does not provide specific		expiration time. This specification does not provide specific
	algorithms, but does impose worst-case constraints on their results.		algorithms, but does impose worst-case constraints on their results.
	A cache MUST NOT use heuristics to determine freshness when an		A cache MUST NOT use heuristics to determine freshness when an
	explicit expiration time is present in the stored response. Because		explicit expiration time is present in the stored response. Because
	of the requirements in Section 3, this means that heuristics can only		of the requirements in Section 3, this means that heuristics can only
	be used on responses without explicit freshness whose status codes		be used on responses without explicit freshness whose status codes
	are defined as "heuristically cacheable" (e.g., see Section 10.1 of		are defined as "heuristically cacheable" (e.g., see Section 14.1 of
	[Semantics]), and those responses without explicit freshness that		[Semantics]), and those responses without explicit freshness that
	have been marked as explicitly cacheable (e.g., with a "public"		have been marked as explicitly cacheable (e.g., with a "public"
	response directive).		response directive).
	Note that in previous specifications heuristically cacheable response		Note that in previous specifications heuristically cacheable response
	status codes were called "cacheable by default."		status codes were called "cacheable by default."
	If the response has a Last-Modified header field (Section 11.2.2 of		If the response has a Last-Modified header field (Section 7.9.2 of
	[Semantics]), caches are encouraged to use a heuristic expiration		[Semantics]), caches are encouraged to use a heuristic expiration
	value that is no more than some fraction of the interval since that		value that is no more than some fraction of the interval since that
	time. A typical setting of this fraction might be 10%.		time. A typical setting of this fraction might be 10%.
	| *Note:* Section 13.9 of [RFC2616] prohibited caches from		| *Note:* Section 13.9 of [RFC2616] prohibited caches from
	| calculating heuristic freshness for URIs with query components		| calculating heuristic freshness for URIs with query components
	| (i.e., those containing '?'). In practice, this has not been		| (i.e., those containing '?'). In practice, this has not been
	| widely implemented. Therefore, origin servers are encouraged		| widely implemented. Therefore, origin servers are encouraged
	| to send explicit directives (e.g., Cache-Control: no-cache) if		| to send explicit directives (e.g., Cache-Control: no-cache) if
	| they wish to prevent caching.		| they wish to prevent caching.
	skipping to change at page 15, line 47 ¶		skipping to change at page 15, line 47 ¶
	been in transit along network paths.		been in transit along network paths.
	Age calculation uses the following data:		Age calculation uses the following data:
	age_value The term "age_value" denotes the value of the Age header		age_value The term "age_value" denotes the value of the Age header
	field (Section 5.1), in a form appropriate for arithmetic		field (Section 5.1), in a form appropriate for arithmetic
	operation; or 0, if not available.		operation; or 0, if not available.
	date_value The term "date_value" denotes the value of the Date		date_value The term "date_value" denotes the value of the Date
	header field, in a form appropriate for arithmetic operations.		header field, in a form appropriate for arithmetic operations.
	See Section 11.1.1 of [Semantics] for the definition of the Date		See Section 9.2.2 of [Semantics] for the definition of the Date
	header field, and for requirements regarding responses without it.		header field, and for requirements regarding responses without it.
	now The term "now" means "the current value of the clock at the host		now The term "now" means "the current value of the clock at the host
	performing the calculation". A host ought to use NTP ([RFC5905])		performing the calculation". A host ought to use NTP ([RFC5905])
	or some similar protocol to synchronize its clocks to Coordinated		or some similar protocol to synchronize its clocks to Coordinated
	Universal Time.		Universal Time.
	request_time The current value of the clock at the host at the time		request_time The current value of the clock at the host at the time
	the request resulting in the stored response was made.		the request resulting in the stored response was made.
	skipping to change at page 17, line 22 ¶		skipping to change at page 17, line 22 ¶
	or doing so is explicitly permitted by the client or origin server		or doing so is explicitly permitted by the client or origin server
	(e.g., by the max-stale request directive in Section 5.2.1, by		(e.g., by the max-stale request directive in Section 5.2.1, by
	extension directives such as those defined in [RFC5861], or by		extension directives such as those defined in [RFC5861], or by
	configuration in accordance with an out-of-band contract).		configuration in accordance with an out-of-band contract).
	4.3. Validation		4.3. Validation
	When a cache has one or more stored responses for a requested URI,		When a cache has one or more stored responses for a requested URI,
	but cannot serve any of them (e.g., because they are not fresh, or		but cannot serve any of them (e.g., because they are not fresh, or
	one cannot be selected; see Section 4.1), it can use the conditional		one cannot be selected; see Section 4.1), it can use the conditional
	request mechanism Section 9.2 of [Semantics] in the forwarded request		request mechanism Section 12.1 of [Semantics] in the forwarded
	to give the next inbound server an opportunity to select a valid		request to give the next inbound server an opportunity to select a
	stored response to use, updating the stored metadata in the process,		valid stored response to use, updating the stored metadata in the
	or to replace the stored response(s) with a new response. This		process, or to replace the stored response(s) with a new response.
	process is known as "validating" or "revalidating" the stored		This process is known as "validating" or "revalidating" the stored
	response.		response.
	4.3.1. Sending a Validation Request		4.3.1. Sending a Validation Request
	When generating a conditional request for validation, a cache starts		When generating a conditional request for validation, a cache starts
	with either a request it is attempting to satisfy, or - if it is		with either a request it is attempting to satisfy, or - if it is
	initiating the request independently - it synthesises a request using		initiating the request independently - it synthesises a request using
	a stored response by copying the method, target URI, and request		a stored response by copying the method, target URI, and request
	header fields identified by the Vary header field Section 4.1.		header fields identified by the Vary header field Section 4.1.
	It then updates that request with one or more precondition header		It then updates that request with one or more precondition header
	fields. These contain validator metadata sourced from stored		fields. These contain validator metadata sourced from stored
	response(s) that have the same cache key.		response(s) that have the same cache key.
	The precondition header fields are then compared by recipients to		The precondition header fields are then compared by recipients to
	determine whether any stored response is equivalent to a current		determine whether any stored response is equivalent to a current
	representation of the resource.		representation of the resource.
	One such validator is the timestamp given in a Last-Modified header		One such validator is the timestamp given in a Last-Modified header
	field (Section 11.2.2 of [Semantics]), which can be used in an If-		field (Section 7.9.2 of [Semantics]), which can be used in an If-
	Modified-Since header field for response validation, or in an If-		Modified-Since header field for response validation, or in an If-
	Unmodified-Since or If-Range header field for representation		Unmodified-Since or If-Range header field for representation
	selection (i.e., the client is referring specifically to a previously		selection (i.e., the client is referring specifically to a previously
	obtained representation with that timestamp).		obtained representation with that timestamp).
	Another validator is the entity-tag given in an ETag field		Another validator is the entity-tag given in an ETag field
	(Section 11.2.3 of [Semantics]). One or more entity-tags, indicating		(Section 7.9.3 of [Semantics]). One or more entity-tags, indicating
	one or more stored responses, can be used in an If-None-Match header		one or more stored responses, can be used in an If-None-Match header
	field for response validation, or in an If-Match or If-Range header		field for response validation, or in an If-Match or If-Range header
	field for representation selection (i.e., the client is referring		field for representation selection (i.e., the client is referring
	specifically to one or more previously obtained representations with		specifically to one or more previously obtained representations with
	the listed entity-tags).		the listed entity-tags).
	4.3.2. Handling a Received Validation Request		4.3.2. Handling a Received Validation Request
	Each client in the request chain may have its own cache, so it is		Each client in the request chain may have its own cache, so it is
	common for a cache at an intermediary to receive conditional requests		common for a cache at an intermediary to receive conditional requests
	skipping to change at page 18, line 35 ¶		skipping to change at page 18, line 35 ¶
	received in that request with respect to the corresponding validators		received in that request with respect to the corresponding validators
	contained within the selected response. A cache MUST NOT evaluate		contained within the selected response. A cache MUST NOT evaluate
	conditional header fields that only apply to an origin server, occur		conditional header fields that only apply to an origin server, occur
	in a request with semantics that cannot be satisfied with a cached		in a request with semantics that cannot be satisfied with a cached
	response, or occur in a request with a target resource for which it		response, or occur in a request with a target resource for which it
	has no stored responses; such preconditions are likely intended for		has no stored responses; such preconditions are likely intended for
	some other (inbound) server.		some other (inbound) server.
	The proper evaluation of conditional requests by a cache depends on		The proper evaluation of conditional requests by a cache depends on
	the received precondition header fields and their precedence, as		the received precondition header fields and their precedence, as
	defined in Section 9.2.2 of [Semantics]. The If-Match and If-		defined in Section 12.3 of [Semantics]. The If-Match and If-
	Unmodified-Since conditional header fields are not applicable to a		Unmodified-Since conditional header fields are not applicable to a
	cache.		cache.
	A request containing an If-None-Match header field (Section 9.2.4 of		A request containing an If-None-Match header field (Section 12.1.2 of
	[Semantics]) indicates that the client wants to validate one or more		[Semantics]) indicates that the client wants to validate one or more
	of its own stored responses in comparison to whichever stored		of its own stored responses in comparison to whichever stored
	response is selected by the cache. If the field value is "*", or if		response is selected by the cache. If the field value is "*", or if
	the field value is a list of entity-tags and at least one of them		the field value is a list of entity-tags and at least one of them
	matches the entity-tag of the selected stored response, a cache		matches the entity-tag of the selected stored response, a cache
	recipient SHOULD generate a 304 (Not Modified) response (using the		recipient SHOULD generate a 304 (Not Modified) response (using the
	metadata of the selected stored response) instead of sending that		metadata of the selected stored response) instead of sending that
	stored response.		stored response.
	When a cache decides to revalidate its own stored responses for a		When a cache decides to revalidate its own stored responses for a
	skipping to change at page 19, line 16 ¶		skipping to change at page 19, line 16 ¶
	content, the cache MUST NOT include its entity-tag in the union		content, the cache MUST NOT include its entity-tag in the union
	unless the request is for a range that would be fully satisfied by		unless the request is for a range that would be fully satisfied by
	that partial stored response. If the response to the forwarded		that partial stored response. If the response to the forwarded
	request is 304 (Not Modified) and has an ETag field value with an		request is 304 (Not Modified) and has an ETag field value with an
	entity-tag that is not in the client's list, the cache MUST generate		entity-tag that is not in the client's list, the cache MUST generate
	a 200 (OK) response for the client by reusing its corresponding		a 200 (OK) response for the client by reusing its corresponding
	stored response, as updated by the 304 response metadata		stored response, as updated by the 304 response metadata
	(Section 4.3.4).		(Section 4.3.4).
	If an If-None-Match header field is not present, a request containing		If an If-None-Match header field is not present, a request containing
	an If-Modified-Since header field (Section 9.2.5 of [Semantics])		an If-Modified-Since header field (Section 12.1.3 of [Semantics])
	indicates that the client wants to validate one or more of its own		indicates that the client wants to validate one or more of its own
	stored responses by modification date. A cache recipient SHOULD		stored responses by modification date. A cache recipient SHOULD
	generate a 304 (Not Modified) response (using the metadata of the		generate a 304 (Not Modified) response (using the metadata of the
	selected stored response) if one of the following cases is true: 1)		selected stored response) if one of the following cases is true: 1)
	the selected stored response has a Last-Modified field value that is		the selected stored response has a Last-Modified field value that is
	earlier than or equal to the conditional timestamp; 2) no Last-		earlier than or equal to the conditional timestamp; 2) no Last-
	Modified field is present in the selected stored response, but it has		Modified field is present in the selected stored response, but it has
	a Date field value that is earlier than or equal to the conditional		a Date field value that is earlier than or equal to the conditional
	timestamp; or, 3) neither Last-Modified nor Date is present in the		timestamp; or, 3) neither Last-Modified nor Date is present in the
	selected stored response, but the cache recorded it as having been		selected stored response, but the cache recorded it as having been
	received at a time earlier than or equal to the conditional		received at a time earlier than or equal to the conditional
	timestamp.		timestamp.
	A cache that implements partial responses to range requests, as		A cache that implements partial responses to range requests, as
	defined in Section 9.3 of [Semantics], also needs to evaluate a		defined in Section 13.2 of [Semantics], also needs to evaluate a
	received If-Range header field (Section 9.2.7 of [Semantics])		received If-Range header field (Section 12.1.5 of [Semantics])
	regarding its selected stored response.		regarding its selected stored response.
	4.3.3. Handling a Validation Response		4.3.3. Handling a Validation Response
	Cache handling of a response to a conditional request depends upon		Cache handling of a response to a conditional request depends upon
	its status code:		its status code:
	o A 304 (Not Modified) response status code indicates that the		o A 304 (Not Modified) response status code indicates that the
	stored response can be updated and reused; see Section 4.3.4.		stored response can be updated and reused; see Section 4.3.4.
	skipping to change at page 20, line 21 ¶		skipping to change at page 20, line 21 ¶
	4.3.4. Freshening Stored Responses upon Validation		4.3.4. Freshening Stored Responses upon Validation
	When a cache receives a 304 (Not Modified) response and already has		When a cache receives a 304 (Not Modified) response and already has
	one or more stored 200 (OK) responses for the applicable cache key,		one or more stored 200 (OK) responses for the applicable cache key,
	the cache needs to identify which (if any) are to be updated by the		the cache needs to identify which (if any) are to be updated by the
	new information provided, and then do so.		new information provided, and then do so.
	The stored response(s) to update are identified by using the first		The stored response(s) to update are identified by using the first
	match (if any) of:		match (if any) of:
	o If the new response contains a strong validator (see		o If the new response contains a strong validator (see Section 7.9.1
	Section 11.2.1 of [Semantics]), then that strong validator		of [Semantics]), then that strong validator identifies the
	identifies the selected representation for update. All the stored		selected representation for update. All the stored responses with
	responses with the same strong validator are identified for		the same strong validator are identified for update. If none of
	update. If none of the stored responses contain the same strong		the stored responses contain the same strong validator, then the
	validator, then the cache MUST NOT use the new response to update		cache MUST NOT use the new response to update any stored
	any stored responses.		responses.
	o If the new response contains a weak validator and that validator		o If the new response contains a weak validator and that validator
	corresponds to one of the cache's stored responses, then the most		corresponds to one of the cache's stored responses, then the most
	recent of those matching stored responses is identified for		recent of those matching stored responses is identified for
	update.		update.
	o If the new response does not include any form of validator (such		o If the new response does not include any form of validator (such
	as where a client generates an If-Modified-Since request from a		as where a client generates an If-Modified-Since request from a
	source other than the Last-Modified response header field), and		source other than the Last-Modified response header field), and
	there is only one stored response, and that stored response also		there is only one stored response, and that stored response also
	skipping to change at page 26, line 13 ¶		skipping to change at page 26, line 13 ¶
	be vulnerable to eavesdropping.		be vulnerable to eavesdropping.
	Note that if a request containing this directive is satisfied from a		Note that if a request containing this directive is satisfied from a
	cache, the no-store request directive does not apply to the already		cache, the no-store request directive does not apply to the already
	stored response.		stored response.
	5.2.1.6. no-transform		5.2.1.6. no-transform
	The "no-transform" request directive indicates that the client is		The "no-transform" request directive indicates that the client is
	asking for intermediaries to avoid transforming the payload, as		asking for intermediaries to avoid transforming the payload, as
	defined in Section 6.6.2 of [Semantics].		defined in Section 6.5 of [Semantics].
	5.2.1.7. only-if-cached		5.2.1.7. only-if-cached
	The "only-if-cached" request directive indicates that the client only		The "only-if-cached" request directive indicates that the client only
	wishes to obtain a stored response. Caches that honor this request		wishes to obtain a stored response. Caches that honor this request
	directive SHOULD, upon receiving it, either respond using a stored		directive SHOULD, upon receiving it, either respond using a stored
	response consistent with the other constraints of the request, or		response consistent with the other constraints of the request, or
	respond with a 504 (Gateway Timeout) status code.		respond with a 504 (Gateway Timeout) status code.
	5.2.2. Response Cache-Control Directives		5.2.2. Response Cache-Control Directives
	skipping to change at page 28, line 26 ¶		skipping to change at page 28, line 26 ¶
	This directive is NOT a reliable or sufficient mechanism for ensuring		This directive is NOT a reliable or sufficient mechanism for ensuring
	privacy. In particular, malicious or compromised caches might not		privacy. In particular, malicious or compromised caches might not
	recognize or obey this directive, and communications networks might		recognize or obey this directive, and communications networks might
	be vulnerable to eavesdropping.		be vulnerable to eavesdropping.
	5.2.2.5. no-transform		5.2.2.5. no-transform
	The "no-transform" response directive indicates that an intermediary		The "no-transform" response directive indicates that an intermediary
	(regardless of whether it implements a cache) MUST NOT transform the		(regardless of whether it implements a cache) MUST NOT transform the
	payload, as defined in Section 6.6.2 of [Semantics].		payload, as defined in Section 6.5 of [Semantics].
	5.2.2.6. public		5.2.2.6. public
	The "public" response directive indicates that a cache MAY store the		The "public" response directive indicates that a cache MAY store the
	response even if it would otherwise be prohibited, subject to the		response even if it would otherwise be prohibited, subject to the
	constraints defined in Section 3. In other words, public explicitly		constraints defined in Section 3. In other words, public explicitly
	marks the response as cacheable. For example, public permits a		marks the response as cacheable. For example, public permits a
	shared cache to reuse a response to a request containing an		shared cache to reuse a response to a request containing an
	Authorization header field (Section 3.3).		Authorization header field (Section 3.3).
	skipping to change at page 32, line 18 ¶		skipping to change at page 32, line 18 ¶
	The "Expires" header field gives the date/time after which the		The "Expires" header field gives the date/time after which the
	response is considered stale. See Section 4.2 for further discussion		response is considered stale. See Section 4.2 for further discussion
	of the freshness model.		of the freshness model.
	The presence of an Expires field does not imply that the original		The presence of an Expires field does not imply that the original
	resource will change or cease to exist at, before, or after that		resource will change or cease to exist at, before, or after that
	time.		time.
	The Expires value is an HTTP-date timestamp, as defined in		The Expires value is an HTTP-date timestamp, as defined in
	Section 5.4.1.5 of [Semantics].		Section 5.7.7 of [Semantics].
	Expires = HTTP-date		Expires = HTTP-date
	For example		For example
	Expires: Thu, 01 Dec 1994 16:00:00 GMT		Expires: Thu, 01 Dec 1994 16:00:00 GMT
	A cache recipient MUST interpret invalid date formats, especially the		A cache recipient MUST interpret invalid date formats, especially the
	value "0", as representing a time in the past (i.e., "already		value "0", as representing a time in the past (i.e., "already
	expired").		expired").
	skipping to change at page 35, line 47 ¶		skipping to change at page 35, line 47 ¶
	Please add a note to the "Hypertext Transfer Protocol (HTTP) Warn		Please add a note to the "Hypertext Transfer Protocol (HTTP) Warn
	Codes" registry at <https://www.iana.org/assignments/http-warn-codes>		Codes" registry at <https://www.iana.org/assignments/http-warn-codes>
	to the effect that Warning is obsoleted.		to the effect that Warning is obsoleted.
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	[Messaging]		[Messaging]
	Fielding, R., Ed., Nottingham, M., Ed., and J. F. Reschke,		Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
	Ed., "HTTP/1.1 Messaging", Work in Progress, Internet-		Ed., "HTTP/1.1 Messaging", Work in Progress, Internet-
	Draft, draft-ietf-httpbis-messaging-11, August 27, 2020,		Draft, draft-ietf-httpbis-messaging-12, October 2, 2020,
	<https://tools.ietf.org/html/draft-ietf-httpbis-messaging-		<https://tools.ietf.org/html/draft-ietf-httpbis-messaging-
	11>.		12>.
	[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
	Resource Identifier (URI): Generic Syntax", STD 66,
	RFC 3986, DOI 10.17487/RFC3986, January 2005,
	<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>.
	[RFC7405] Kyzivat, P., "Case-Sensitive String Support in ABNF",		[RFC7405] Kyzivat, P., "Case-Sensitive String Support in ABNF",
	RFC 7405, DOI 10.17487/RFC7405, December 2014,		RFC 7405, DOI 10.17487/RFC7405, December 2014,
	<https://www.rfc-editor.org/info/rfc7405>.		<https://www.rfc-editor.org/info/rfc7405>.
	[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>.
	[Semantics]		[Semantics]
	Fielding, R., Ed., Nottingham, M., Ed., and J. F. Reschke,		Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
	Ed., "HTTP Semantics", Work in Progress, Internet-Draft,		Ed., "HTTP Semantics", Work in Progress, Internet-Draft,
	draft-ietf-httpbis-semantics-11, August 27, 2020,		draft-ietf-httpbis-semantics-12, October 2, 2020,
	<https://tools.ietf.org/html/draft-ietf-httpbis-semantics-		<https://tools.ietf.org/html/draft-ietf-httpbis-semantics-
	11>.		12>.
	[USASCII] American National Standards Institute, "Coded Character		[USASCII] American National Standards Institute, "Coded Character
	Set -- 7-bit American Standard Code for Information		Set -- 7-bit American Standard Code for Information
	Interchange", ANSI X3.4, 1986.		Interchange", ANSI X3.4, 1986.
	9.2. Informative References		9.2. Informative References
	[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,
	skipping to change at page 37, line 27 ¶		skipping to change at page 37, line 22 ¶
	<https://www.rfc-editor.org/info/rfc7234>.		<https://www.rfc-editor.org/info/rfc7234>.
	[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for		[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
	Writing an IANA Considerations Section in RFCs", BCP 26,		Writing an IANA Considerations Section in RFCs", BCP 26,
	RFC 8126, DOI 10.17487/RFC8126, June 2017,		RFC 8126, DOI 10.17487/RFC8126, June 2017,
	<https://www.rfc-editor.org/info/rfc8126>.		<https://www.rfc-editor.org/info/rfc8126>.
	Appendix A. Collected ABNF		Appendix A. Collected ABNF
	In the collected ABNF below, list rules are expanded as per		In the collected ABNF below, list rules are expanded as per
	Section 5.5.1 of [Semantics].		Section 5.7.1.1 of [Semantics].
	Age = delta-seconds		Age = delta-seconds
	Cache-Control = [ cache-directive *( OWS "," OWS cache-directive ) ]		Cache-Control = [ cache-directive *( OWS "," OWS cache-directive ) ]
	Expires = HTTP-date		Expires = HTTP-date
	HTTP-date = <HTTP-date, see [Semantics], Section 5.4.1.5>		HTTP-date = <HTTP-date, see [Semantics], Section 5.7.7>
	OWS = <OWS, see [Semantics], Section 1.6.1>		OWS = <OWS, see [Semantics], Section 5.7.3>
	cache-directive = token [ "=" ( token / quoted-string ) ]		cache-directive = token [ "=" ( token / quoted-string ) ]
	delta-seconds = 1*DIGIT		delta-seconds = 1*DIGIT
	field-name = <field-name, see [Semantics], Section 5.3>		field-name = <field-name, see [Semantics], Section 5.4.3>
	quoted-string = <quoted-string, see [Semantics], Section 5.4.1.2>		quoted-string = <quoted-string, see [Semantics], Section 5.7.4>
	token = <token, see [Semantics], Section 5.4.1.1>		token = <token, see [Semantics], Section 5.7.2>
	Appendix B. Changes from RFC 7234		Appendix B. Changes from RFC 7234
	Handling invalid and multiple Age header field values has been		Handling invalid and multiple Age header field values has been
	clarified. (Section 5.1)		clarified. (Section 5.1)
	Some cache directives defined by this specification now have stronger		Some cache directives defined by this specification now have stronger
	prohibitions against generating the quoted form of their values,		prohibitions against generating the quoted form of their values,
	since this has been found to create interoperability problems.		since this has been found to create interoperability problems.
	Consumers of extension cache directives are no longer required to		Consumers of extension cache directives are no longer required to
	accept both token and quoted-string forms, but they still need to		accept both token and quoted-string forms, but they still need to
	skipping to change at page 42, line 5 ¶		skipping to change at page 42, line 5 ¶
	issues/193>)		issues/193>)
	o Switch to xml2rfc v3 mode for draft generation		o Switch to xml2rfc v3 mode for draft generation
	(<https://github.com/httpwg/http-core/issues/394>)		(<https://github.com/httpwg/http-core/issues/394>)
	C.12. Since draft-ietf-httpbis-cache-10		C.12. Since draft-ietf-httpbis-cache-10
	o In Section 5.2 (Cache-Control), adjust ABNF to allow empty lists		o In Section 5.2 (Cache-Control), adjust ABNF to allow empty lists
	(<https://github.com/httpwg/http-core/issues/210>)		(<https://github.com/httpwg/http-core/issues/210>)
			C.13. Since draft-ietf-httpbis-cache-11
			o None.
	Acknowledgments		Acknowledgments
	See Appendix "Acknowledgments" of [Semantics].		See Appendix "Acknowledgments" of [Semantics].
	Authors' Addresses		Authors' Addresses
	Roy T. Fielding (editor)		Roy T. Fielding (editor)
	Adobe		Adobe
	345 Park Ave		345 Park Ave
	San Jose, CA 95110		San Jose, CA 95110
	skipping to change at page 42, line 28 ¶		skipping to change at page 42, line 32 ¶
	URI: https://roy.gbiv.com/		URI: https://roy.gbiv.com/
	Mark Nottingham (editor)		Mark Nottingham (editor)
	Fastly		Fastly
	Prahran VIC		Prahran VIC
	Australia		Australia
	Email: mnot@mnot.net		Email: mnot@mnot.net
	URI: https://www.mnot.net/		URI: https://www.mnot.net/
	Julian F. Reschke (editor)		Julian Reschke (editor)
	greenbytes GmbH		greenbytes GmbH
	Hafenweg 16		Hafenweg 16
	48155 Münster		48155 Münster
	Germany		Germany
	Email: julian.reschke@greenbytes.de		Email: julian.reschke@greenbytes.de
	URI: https://greenbytes.de/tech/webdav/		URI: https://greenbytes.de/tech/webdav/
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