draft-ietf-httpbis-p4-conditional-02.txt		draft-ietf-httpbis-p4-conditional-03.txt
	Network Working Group R. Fielding, Ed.		Network Working Group R. Fielding, Ed.
	Internet-Draft Day Software		Internet-Draft Day Software
	Obsoletes: 2616 (if approved) J. Gettys		Obsoletes: 2616 (if approved) J. Gettys
	Intended status: Standards Track One Laptop per Child		Intended status: Standards Track One Laptop per Child
	Expires: August 27, 2008 J. Mogul		Expires: December 19, 2008 J. Mogul
	HP		HP
	H. Frystyk		H. Frystyk
	Microsoft		Microsoft
	L. Masinter		L. Masinter
	Adobe Systems		Adobe Systems
	P. Leach		P. Leach
	Microsoft		Microsoft
	T. Berners-Lee		T. Berners-Lee
	W3C/MIT		W3C/MIT
	Y. Lafon, Ed.		Y. Lafon, Ed.
	W3C		W3C
	J. Reschke, Ed.		J. Reschke, Ed.
	greenbytes		greenbytes
	February 24, 2008		June 17, 2008
	HTTP/1.1, part 4: Conditional Requests		HTTP/1.1, part 4: Conditional Requests
	draft-ietf-httpbis-p4-conditional-02		draft-ietf-httpbis-p4-conditional-03
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, each author represents that any		By submitting this Internet-Draft, each author represents that any
	applicable patent or other IPR claims of which he or she is aware		applicable patent or other IPR claims of which he or she is aware
	have been or will be disclosed, and any of which he or she becomes		have been or will be disclosed, and any of which he or she becomes
	aware will be disclosed, in accordance with Section 6 of BCP 79.		aware will be disclosed, in accordance with Section 6 of BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
	skipping to change at page 1, line 49		skipping to change at page 1, line 49
	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."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/1id-abstracts.txt.		http://www.ietf.org/ietf/1id-abstracts.txt.
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	This Internet-Draft will expire on August 27, 2008.		This Internet-Draft will expire on December 19, 2008.
	Copyright Notice
	Copyright (C) The IETF Trust (2008).
	Abstract		Abstract
	The Hypertext Transfer Protocol (HTTP) is an application-level		The Hypertext Transfer Protocol (HTTP) is an application-level
	protocol for distributed, collaborative, hypermedia information		protocol for distributed, collaborative, hypermedia information
	systems. HTTP has been in use by the World Wide Web global		systems. HTTP has been in use by the World Wide Web global
	information initiative since 1990. This document is Part 4 of the		information initiative since 1990. This document is Part 4 of the
	seven-part specification that defines the protocol referred to as		seven-part specification that defines the protocol referred to as
	"HTTP/1.1" and, taken together, obsoletes RFC 2616. Part 4 defines		"HTTP/1.1" and, taken together, obsoletes RFC 2616. Part 4 defines
	request header fields for indicating conditional requests and the		request header fields for indicating conditional requests and the
	rules for constructing responses to those requests.		rules for constructing responses to those requests.
	Editorial Note (To be removed by RFC Editor)		Editorial Note (To be removed by RFC Editor)
	Discussion of this draft should take place on the HTTPBIS working		Discussion of this draft should take place on the HTTPBIS working
	group mailing list (ietf-http-wg@w3.org). The current issues list is		group mailing list (ietf-http-wg@w3.org). The current issues list is
	at <http://www.tools.ietf.org/wg/httpbis/trac/report/11> and related		at <http://www.tools.ietf.org/wg/httpbis/trac/report/11> and related
	documents (including fancy diffs) can be found at		documents (including fancy diffs) can be found at
	<http://www.tools.ietf.org/wg/httpbis/>.		<http://www.tools.ietf.org/wg/httpbis/>.
	This draft incorporates those issue resolutions that were either		The changes in this draft are summarized in Appendix B.4.
	collected in the original RFC2616 errata list
	(<http://purl.org/NET/http-errata>), or which were agreed upon on the
	mailing list between October 2006 and November 2007 (as published in
	"draft-lafon-rfc2616bis-03").
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
	1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 4		1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 4
	2. Notational Conventions and Generic Grammar . . . . . . . . . . 4		2. Notational Conventions and Generic Grammar . . . . . . . . . . 4
	3. Entity Tags . . . . . . . . . . . . . . . . . . . . . . . . . 5		3. Entity Tags . . . . . . . . . . . . . . . . . . . . . . . . . 5
	4. Status Code Definitions . . . . . . . . . . . . . . . . . . . 5		4. Status Code Definitions . . . . . . . . . . . . . . . . . . . 5
	4.1. 304 Not Modified . . . . . . . . . . . . . . . . . . . . . 5		4.1. 304 Not Modified . . . . . . . . . . . . . . . . . . . . . 5
	4.2. 412 Precondition Failed . . . . . . . . . . . . . . . . . 6		4.2. 412 Precondition Failed . . . . . . . . . . . . . . . . . 6
	5. Weak and Strong Validators . . . . . . . . . . . . . . . . . . 6		5. Weak and Strong Validators . . . . . . . . . . . . . . . . . . 6
	6. Rules for When to Use Entity Tags and Last-Modified Dates . . 9		6. Rules for When to Use Entity Tags and Last-Modified Dates . . 9
	7. Header Field Definitions . . . . . . . . . . . . . . . . . . . 11		7. Header Field Definitions . . . . . . . . . . . . . . . . . . . 11
	7.1. ETag . . . . . . . . . . . . . . . . . . . . . . . . . . . 11		7.1. ETag . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
	7.2. If-Match . . . . . . . . . . . . . . . . . . . . . . . . . 12		7.2. If-Match . . . . . . . . . . . . . . . . . . . . . . . . . 11
	7.3. If-Modified-Since . . . . . . . . . . . . . . . . . . . . 13		7.3. If-Modified-Since . . . . . . . . . . . . . . . . . . . . 13
	7.4. If-None-Match . . . . . . . . . . . . . . . . . . . . . . 14		7.4. If-None-Match . . . . . . . . . . . . . . . . . . . . . . 14
	7.5. If-Unmodified-Since . . . . . . . . . . . . . . . . . . . 16		7.5. If-Unmodified-Since . . . . . . . . . . . . . . . . . . . 15
	7.6. Last-Modified . . . . . . . . . . . . . . . . . . . . . . 16		7.6. Last-Modified . . . . . . . . . . . . . . . . . . . . . . 16
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
			8.1. Message Header Registration . . . . . . . . . . . . . . . 17
	9. Security Considerations . . . . . . . . . . . . . . . . . . . 17		9. Security Considerations . . . . . . . . . . . . . . . . . . . 17
	10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17		10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17		11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
	11.1. Normative References . . . . . . . . . . . . . . . . . . . 17		11.1. Normative References . . . . . . . . . . . . . . . . . . . 18
	11.2. Informative References . . . . . . . . . . . . . . . . . . 18		11.2. Informative References . . . . . . . . . . . . . . . . . . 18
	Appendix A. Compatibility with Previous Versions . . . . . . . . 18		Appendix A. Compatibility with Previous Versions . . . . . . . . 18
	A.1. Changes from RFC 2616 . . . . . . . . . . . . . . . . . . 18		A.1. Changes from RFC 2616 . . . . . . . . . . . . . . . . . . 18
	Appendix B. Change Log (to be removed by RFC Editor before		Appendix B. Change Log (to be removed by RFC Editor before
	publication) . . . . . . . . . . . . . . . . . . . . 18		publication) . . . . . . . . . . . . . . . . . . . . 19
	B.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 18		B.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 19
	B.2. Since draft-ietf-httpbis-p4-conditional-00 . . . . . . . . 18		B.2. Since draft-ietf-httpbis-p4-conditional-00 . . . . . . . . 19
	B.3. Since draft-ietf-httpbis-p4-conditional-01 . . . . . . . . 18		B.3. Since draft-ietf-httpbis-p4-conditional-01 . . . . . . . . 19
			B.4. Since draft-ietf-httpbis-p4-conditional-02 . . . . . . . . 19
	Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19		Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20
	Intellectual Property and Copyright Statements . . . . . . . . . . 23		Intellectual Property and Copyright Statements . . . . . . . . . . 24
	1. Introduction		1. Introduction
	This document defines HTTP/1.1 response metadata for indicating		This document defines HTTP/1.1 response metadata for indicating
	potential changes to payload content, including modification time		potential changes to payload content, including modification time
	stamps and opaque entity-tags, and the HTTP conditional request		stamps and opaque entity-tags, and the HTTP conditional request
	mechanisms that allow preconditions to be placed on a request method.		mechanisms that allow preconditions to be placed on a request method.
	Conditional GET requests allow for efficient cache updates. Other		Conditional GET requests allow for efficient cache updates. Other
	conditional request methods are used to protect against overwriting		conditional request methods are used to protect against overwriting
	or misunderstanding the state of a resource that has been changed		or misunderstanding the state of a resource that has been changed
	skipping to change at page 7, line 40		skipping to change at page 7, line 40
	and includes the validator in a validating header field, or when a		and includes the validator in a validating header field, or when a
	server compares two validators.		server compares two validators.
	Strong validators are usable in any context. Weak validators are		Strong validators are usable in any context. Weak validators are
	only usable in contexts that do not depend on exact equality of an		only usable in contexts that do not depend on exact equality of an
	entity. For example, either kind is usable for a conditional GET of		entity. For example, either kind is usable for a conditional GET of
	a full entity. However, only a strong validator is usable for a sub-		a full entity. However, only a strong validator is usable for a sub-
	range retrieval, since otherwise the client might end up with an		range retrieval, since otherwise the client might end up with an
	internally inconsistent entity.		internally inconsistent entity.
	Clients MAY issue simple (non-subrange) GET requests with either weak		Clients MUST NOT use weak validators in range requests ([Part5]).
	validators or strong validators. Clients MUST NOT use weak
	validators in other forms of request.
	The only function that HTTP/1.1 defines on validators is comparison.		The only function that HTTP/1.1 defines on validators is comparison.
	There are two validator comparison functions, depending on whether		There are two validator comparison functions, depending on whether
	the comparison context allows the use of weak validators or not:		the comparison context allows the use of weak validators or not:
	o The strong comparison function: in order to be considered equal,		o The strong comparison function: in order to be considered equal,
	both validators MUST be identical in every way, and both MUST NOT		both validators MUST be identical in every way, and both MUST NOT
	be weak.		be weak.
	o The weak comparison function: in order to be considered equal,		o The weak comparison function: in order to be considered equal,
	skipping to change at page 9, line 12		skipping to change at page 9, line 10
	Modified values are generated from different clocks, or at somewhat		Modified values are generated from different clocks, or at somewhat
	different times during the preparation of the response. An		different times during the preparation of the response. An
	implementation MAY use a value larger than 60 seconds, if it is		implementation MAY use a value larger than 60 seconds, if it is
	believed that 60 seconds is too short.		believed that 60 seconds is too short.
	If a client wishes to perform a sub-range retrieval on a value for		If a client wishes to perform a sub-range retrieval on a value for
	which it has only a Last-Modified time and no opaque validator, it		which it has only a Last-Modified time and no opaque validator, it
	MAY do this only if the Last-Modified time is strong in the sense		MAY do this only if the Last-Modified time is strong in the sense
	described here.		described here.
	A cache or origin server receiving a conditional request, other than		A cache or origin server receiving a conditional range request
	a full-body GET request, MUST use the strong comparison function to		([Part5]) MUST use the strong comparison function to evaluate the
	evaluate the condition.		condition.
	These rules allow HTTP/1.1 caches and clients to safely perform sub-		These rules allow HTTP/1.1 caches and clients to safely perform sub-
	range retrievals on values that have been obtained from HTTP/1.0		range retrievals on values that have been obtained from HTTP/1.0
	servers.		servers.
	6. Rules for When to Use Entity Tags and Last-Modified Dates		6. Rules for When to Use Entity Tags and Last-Modified Dates
	We adopt a set of rules and recommendations for origin servers,		We adopt a set of rules and recommendations for origin servers,
	clients, and caches regarding when various validator types ought to		clients, and caches regarding when various validator types ought to
	be used, and for what purposes.		be used, and for what purposes.
	skipping to change at page 15, line 16		skipping to change at page 15, line 11
	given and any current entity exists for that resource, then the		given and any current entity exists for that resource, then the
	server MUST NOT perform the requested method, unless required to do		server MUST NOT perform the requested method, unless required to do
	so because the resource's modification date fails to match that		so because the resource's modification date fails to match that
	supplied in an If-Modified-Since header field in the request.		supplied in an If-Modified-Since header field in the request.
	Instead, if the request method was GET or HEAD, the server SHOULD		Instead, if the request method was GET or HEAD, the server SHOULD
	respond with a 304 (Not Modified) response, including the cache-		respond with a 304 (Not Modified) response, including the cache-
	related header fields (particularly ETag) of one of the entities that		related header fields (particularly ETag) of one of the entities that
	matched. For all other request methods, the server MUST respond with		matched. For all other request methods, the server MUST respond with
	a status of 412 (Precondition Failed).		a status of 412 (Precondition Failed).
	See Section 5 for rules on how to determine if two entities tags		See Section 5 for rules on how to determine if two entity tags match.
	match. The weak comparison function can only be used with GET or
	HEAD requests.
	If none of the entity tags match, then the server MAY perform the		If none of the entity tags match, then the server MAY perform the
	requested method as if the If-None-Match header field did not exist,		requested method as if the If-None-Match header field did not exist,
	but MUST also ignore any If-Modified-Since header field(s) in the		but MUST also ignore any If-Modified-Since header field(s) in the
	request. That is, if no entity tags match, then the server MUST NOT		request. That is, if no entity tags match, then the server MUST NOT
	return a 304 (Not Modified) response.		return a 304 (Not Modified) response.
	If the request would, without the If-None-Match header field, result		If the request would, without the If-None-Match header field, result
	in anything other than a 2xx or 304 status, then the If-None-Match		in anything other than a 2xx or 304 status, then the If-None-Match
	header MUST be ignored. (See Section 6 for a discussion of server		header MUST be ignored. (See Section 6 for a discussion of server
	skipping to change at page 17, line 25		skipping to change at page 17, line 16
	near the time that the response is generated.		near the time that the response is generated.
	HTTP/1.1 servers SHOULD send Last-Modified whenever feasible.		HTTP/1.1 servers SHOULD send Last-Modified whenever feasible.
	The Last-Modified entity-header field value is often used as a cache		The Last-Modified entity-header field value is often used as a cache
	validator. In simple terms, a cache entry is considered to be valid		validator. In simple terms, a cache entry is considered to be valid
	if the entity has not been modified since the Last-Modified value.		if the entity has not been modified since the Last-Modified value.
	8. IANA Considerations		8. IANA Considerations
	[[anchor2: TBD.]]		8.1. Message Header Registration
			The Message Header Registry located at <http://www.iana.org/
			assignments/message-headers/message-header-index.html> should be
			updated with the permanent registrations below (see [RFC3864]):
			+---------------------+----------+----------+-------------+
			| Header Field Name | Protocol | Status | Reference |
			+---------------------+----------+----------+-------------+
			| ETag | http | standard | Section 7.1 |
			| If-Match | http | standard | Section 7.2 |
			| If-Modified-Since | http | standard | Section 7.3 |
			| If-None-Match | http | standard | Section 7.4 |
			| If-Unmodified-Since | http | standard | Section 7.5 |
			| Last-Modified | http | standard | Section 7.6 |
			+---------------------+----------+----------+-------------+
			The change controller is: "IETF (iesg@ietf.org) - Internet
			Engineering Task Force".
	9. Security Considerations		9. Security Considerations
	No additional security considerations have been identified beyond		No additional security considerations have been identified beyond
	those applicable to HTTP in general [Part1].		those applicable to HTTP in general [Part1].
	10. Acknowledgments		10. Acknowledgments
	11. References		11. References
	11.1. Normative References		11.1. Normative References
	[Part1] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,		[Part1] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
	Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,		Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
	and J. Reschke, Ed., "HTTP/1.1, part 1: URIs, Connections,		and J. Reschke, Ed., "HTTP/1.1, part 1: URIs, Connections,
	and Message Parsing", draft-ietf-httpbis-p1-messaging-02		and Message Parsing", draft-ietf-httpbis-p1-messaging-03
	(work in progress), February 2008.		(work in progress), June 2008.
	[Part5] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,		[Part5] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
	Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,		Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
	and J. Reschke, Ed., "HTTP/1.1, part 5: Range Requests and		and J. Reschke, Ed., "HTTP/1.1, part 5: Range Requests and
	Partial Responses", draft-ietf-httpbis-p5-range-02 (work		Partial Responses", draft-ietf-httpbis-p5-range-03 (work
	in progress), February 2008.		in progress), June 2008.
	[Part6] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,		[Part6] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
	Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,		Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
	and J. Reschke, Ed., "HTTP/1.1, part 6: Caching",		and J. Reschke, Ed., "HTTP/1.1, part 6: Caching",
	draft-ietf-httpbis-p6-cache-02 (work in progress),		draft-ietf-httpbis-p6-cache-03 (work in progress),
	February 2008.		June 2008.
	[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, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	11.2. Informative References		11.2. Informative References
	[RFC2068] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., and T.		[RFC2068] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., and T.
	Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1",		Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1",
	RFC 2068, January 1997.		RFC 2068, January 1997.
	[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, June 1999.		Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
			[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
			Procedures for Message Header Fields", BCP 90, RFC 3864,
			September 2004.
	Appendix A. Compatibility with Previous Versions		Appendix A. Compatibility with Previous Versions
	A.1. Changes from RFC 2616		A.1. Changes from RFC 2616
			Allow weak entity tags in all requests except range requests
			(Sections 5 and 7.4).
	Appendix B. Change Log (to be removed by RFC Editor before publication)		Appendix B. Change Log (to be removed by RFC Editor before publication)
	B.1. Since RFC2616		B.1. Since RFC2616
	Extracted relevant partitions from [RFC2616].		Extracted relevant partitions from [RFC2616].
	B.2. Since draft-ietf-httpbis-p4-conditional-00		B.2. Since draft-ietf-httpbis-p4-conditional-00
	Closed issues:		Closed issues:
	skipping to change at page 19, line 8		skipping to change at page 19, line 30
	o Move definitions of 304 and 412 condition codes from Part2.		o Move definitions of 304 and 412 condition codes from Part2.
	B.3. Since draft-ietf-httpbis-p4-conditional-01		B.3. Since draft-ietf-httpbis-p4-conditional-01
	Ongoing work on ABNF conversion		Ongoing work on ABNF conversion
	(<http://www3.tools.ietf.org/wg/httpbis/trac/ticket/36>):		(<http://www3.tools.ietf.org/wg/httpbis/trac/ticket/36>):
	o Add explicit references to BNF syntax and rules imported from		o Add explicit references to BNF syntax and rules imported from
	other parts of the specification.		other parts of the specification.
			B.4. Since draft-ietf-httpbis-p4-conditional-02
			Closed issues:
			o <http://www3.tools.ietf.org/wg/httpbis/trac/ticket/116>: "Weak
			ETags on non-GET requests"
			Ongoing work on IANA Message Header Registration
			(<http://www3.tools.ietf.org/wg/httpbis/trac/ticket/40>):
			o Reference RFC 3984, and update header registrations for headers
			defined in this document.
	Index		Index
	3		3
	304 Not Modified (status code) 5		304 Not Modified (status code) 5
	4		4
	412 Precondition Failed (status code) 6		412 Precondition Failed (status code) 6
	E		E
	ETag header 11		ETag header 11
	skipping to change at page 19, line 34		skipping to change at page 20, line 21
	If-Modified-Since 13		If-Modified-Since 13
	If-None-Match 14		If-None-Match 14
	If-Unmodified-Since 16		If-Unmodified-Since 16
	Last-Modified 16		Last-Modified 16
	opaque-tag 5		opaque-tag 5
	weak 5		weak 5
	H		H
	Headers		Headers
	ETag 11		ETag 11
	If-Match 12		If-Match 11
	If-Modified-Since 13		If-Modified-Since 13
	If-None-Match 14		If-None-Match 14
	If-Unmodified-Since 16		If-Unmodified-Since 15
	Last-Modified 16		Last-Modified 16
	I		I
	If-Match header 12		If-Match header 11
	If-Modified-Since header 13		If-Modified-Since header 13
	If-None-Match header 14		If-None-Match header 14
	If-Unmodified-Since header 16		If-Unmodified-Since header 15
	L		L
	Last-Modified header 16		Last-Modified header 16
	S		S
	Status Codes		Status Codes
	304 Not Modified 5		304 Not Modified 5
	412 Precondition Failed 6		412 Precondition Failed 6
	Authors' Addresses		Authors' Addresses
	skipping to change at page 23, line 44		skipping to change at line 1018
	attempt made to obtain a general license or permission for the use of		attempt made to obtain a general license or permission for the use of
	such proprietary rights by implementers or users of this		such proprietary rights by implementers or users of this
	specification can be obtained from the IETF on-line IPR repository at		specification can be obtained from the IETF on-line IPR repository at
	http://www.ietf.org/ipr.		http://www.ietf.org/ipr.
	The IETF invites any interested party to bring to its attention any		The IETF invites any interested party to bring to its attention any
	copyrights, patents or patent applications, or other proprietary		copyrights, patents or patent applications, or other proprietary
	rights that may cover technology that may be required to implement		rights that may cover technology that may be required to implement
	this standard. Please address the information to the IETF at		this standard. Please address the information to the IETF at
	ietf-ipr@ietf.org.		ietf-ipr@ietf.org.
	Acknowledgment
	Funding for the RFC Editor function is provided by the IETF
	Administrative Support Activity (IASA).
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	42 lines changed or deleted		70 lines changed or added
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