rfc9748.txt		rfc9748-test2.txt
	Internet Engineering Task Force (IETF) R. Salz		Internet Engineering Task Force (IETF) R. Salz
	Request for Comments: 9748 Akamai Technologies		Request for Comments: 9748 Akamai Technologies
	Updates: 5905, 5906, 7821, 7822, 8573 February 2025		Updates: 5905, 5906, 7821, 7822, 8573 February 2025
	Category: Standards Track		Category: Standards Track
	ISSN: 2070-1721		ISSN: 2070-1721
	Updating the NTP Registries		Updating the NTP Registries
	Abstract		Abstract
	The Network Time Protocol (NTP) and Network Time Security (NTS)		The Network Time Protocol (NTP) and Network Time Security (NTS)
	documents define a number of registries, collectively called the NTP		documents define a number of registries, collectively called the NTP
	registries.		registries.
	Some registries are correct, but some include incorrect assignments		Some registries are correct, but some include incorrect assignments
	and some don’t follow common practice. For the sake of completeness,		and some don’t follow common practice. For the sake of completeness,
	this document reviews all NTP and NTS registries, and corrects the		this document reviews all NTP and NTS registries, and corrects the
	registries where necessary.		registries where necessary.
	This document updates RFCs 5905, 5906, 7821, 7822, and 8573.		This document updates RFCs 5905, 5906, 7821, 7822, and 8573.
	Status of This Memo		Status of This Memo
	This is an Internet Standards Track document.		This is an Internet Standards Track document.
	This document is a product of the Internet Engineering Task Force		This document is a product of the Internet Engineering Task Force
	(IETF). It represents the consensus of the IETF community. It has		(IETF). It represents the consensus of the IETF community. It has
	received public review and has been approved for publication by the		received public review and has been approved for publication by the
	Internet Engineering Steering Group (IESG). Further information on		Internet Engineering Steering Group (IESG). Further information on
	Internet Standards is available in Section 2 of RFC 7841.		Internet Standards is available in Section 2 of RFC 7841.
	Information about the current status of this document, any errata,		Information about the current status of this document, any errata,
	and how to provide feedback on it may be obtained at		and how to provide feedback on it may be obtained at
	https://www.rfc-editor.org/info/rfc9748.		https://www.rfc-editor.org/info/rfc9748.
	Copyright Notice		Copyright Notice
	Copyright (c) 2025 IETF Trust and the persons identified as the		Copyright (c) 2025 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
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Revised BSD License text as described in Section 4.e of the		include Revised BSD License text as described in Section 4.e of the
	Trust Legal Provisions and are provided without warranty as described		Trust Legal Provisions and are provided without warranty as described
	in the Revised BSD License.		in the Revised BSD License.
	Table of Contents		Table of Contents
	1. Introduction		1. Introduction
	2. Existing Registries		2. Existing Registries
	2.1. Reference ID and Kiss-o'-Death Registries		2.1. Reference ID and Kiss-o'-Death Registries
	2.2. Extension Field Types		2.2. Extension Field Types
	2.3. Network Time Security Registries		2.3. Network Time Security Registries
	3. Registry Updates		3. NTP Registry Updates
	3.1. Guidance to Designated Experts		3.1. Designated Experts
	4. IANA Considerations		4. IANA Considerations
	4.1. NTP Reference Identifier Codes		4.1. NTP Reference Identifier Codes
	4.2. NTP Kiss-o'-Death Codes		4.2. NTP Kiss-o'-Death Codes
	4.3. NTP Extension Field Types		4.3. NTP Extension Field Types
	5. Security Considerations		5. Security Considerations
	6. Normative References		6. Normative References
	Acknowledgements		Acknowledgements
	Author's Address		Author's Address
	1. Introduction		1. Introduction
	The Network Time Protocol (NTP) and Network Time Security (NTS)		The Network Time Protocol (NTP) and Network Time Security (NTS)
	documents define a number of registries, collectively called the NTP		documents define a number of registries, collectively called the NTP
	registries. The NTP registries can all be found at		registries. The NTP registries can all be found at
	<https://www.iana.org/assignments/ntp-parameters> and the NTS		<https://www.iana.org/assignments/ntp-parameters> and the NTS
	registries can all be found at <https://www.iana.org/assignments/		registries can all be found at <https://www.iana.org/assignments/
	nts>.		nts>.
	Some registries are correct, but some include incorrect assignments		Some registries are correct, but some include incorrect assignments
	and some don’t follow common practice. For the sake of completeness,		and some don’t follow common practice. For the sake of completeness,
	this document reviews all NTP and NTS registries, and corrects the		this document reviews all NTP and NTS registries, and corrects the
	registries where necessary.		registries where necessary.
	The bulk of this document can be divided into two parts:		The bulk of this document can be divided into two parts:
	* a summary of the relevant registries, including syntax		* a summary of the relevant registries, including syntax
	requirements, registration procedures, and the defining documents.		requirements, registration procedures, and the defining documents.
	* a revised format and entries for each registry being modified.		* a revised format and entries for each registry being modified.
	2. Existing Registries		2. Existing Registries
	This section describes the registries and the rules for them. It is		This section describes the registries and the rules for them. It is
	intended to be a short summary of the syntax and registration		intended to be a short summary of the syntax and registration
	requirements for each registry. The semantics and protocol		requirements for each registry. The semantics and protocol
	processing rules for each registry -- that is, how an implementation		processing rules for each registry -- that is, how an implementation
	acts when sending or receiving any of the fields -- are not described		acts when sending or receiving any of the fields -- are not described
	here.		here.
	2.1. Reference ID and Kiss-o'-Death Registries		2.1. Reference ID and Kiss-o'-Death Registries
	[RFC5905] defines two registries: "NTP Reference Identifier Codes" in		[RFC5905] defines two registries: "NTP Reference Identifier Codes" in
	Section 7.3 and the "NTP Kiss-o'-Death Codes" in Section 7.4.		Section 7.3 and the "NTP Kiss-o'-Death Codes" in Section 7.4.
	Reference identifiers and kiss codes can be up to four ASCII		Reference identifiers and kiss codes can be up to four ASCII
	characters, padded on the right with all-bits-zero if necessary.		characters, padded on the right with all-bits-zero if necessary.
	Entries that start with 0x58, the ASCII letter uppercase X, are		Entries that start with 0x58, the ASCII letter uppercase X, are
	reserved for Private or Experimental Use. Both registries are First		reserved for Private or Experimental Use. Both registries are First
	Come First Served. The registries were created per Section 16 of		Come First Served. The registries were created per Section 16 of
	[RFC5905].		[RFC5905].
	2.2. Extension Field Types		2.2. Extension Field Types
	Section 7.5 of [RFC5905] defines the on-the-wire format of extension		Section 7.5 of [RFC5905] defines the on-the-wire format of extension
	fields but does not create a registry for them.		fields but does not create a registry for them.
	Section 13 of [RFC5906] mentions the "NTP Extension Field Types"		Section 13 of [RFC5906] mentions the "NTP Extension Field Types"
	registry, and defines it indirectly by defining 30 extensions (10		registry, and defines it indirectly by defining 30 extensions (10
	each for request, response, and error response). It does not provide		each for request, response, and error response). It does not provide
	a formal definition of the columns in the registry. Section 10 of		a formal definition of the columns in the registry. Section 10 of
	[RFC5906] splits the Field Type into four subfields, only for use		[RFC5906] splits the Field Type into four subfields, only for use
	within the Autokey extensions.		within the Autokey extensions.
	[RFC7821] adds a new entry, Checksum Complement, to the "NTP		[RFC7821] adds a new entry, Checksum Complement, to the "NTP
	Extension Field Types" registry.		Extension Field Types" registry.
	[RFC7822] clarifies the processing rules for Extension Field Types,		[RFC7822] clarifies the processing rules for Extension Field Types,
	particularly around the interaction with the Message Authentication		particularly around the interaction with the Message Authentication
	Code (MAC) field. NTPv4 packets may contain a MAC that appears where		Code (MAC) field. NTPv4 packets may contain a MAC that appears where
	one would expect the next extension field header.		one would expect the next extension field header.
	[RFC8573] changes the cryptography used in the MAC field.		[RFC8573] changes the cryptography used in the MAC field.
	[RFC8915] adds four new entries to the "NTP Extension Field Types"		[RFC8915] adds four new entries to the "NTP Extension Field Types"
	registry.		registry.
	The following problems exist with the current registry:		The following problems exist with the current registry:
	* Many of the entries in the "NTP Extension Field Types" registry		* Many of the entries in the "NTP Extension Field Types" registry
	have swapped some of the nibbles; for example, 0x0302 was listed		have swapped some of the nibbles; for example, 0x0302 was listed
	for Cookie Message Request instead of 0x0203. The errors are due		for Cookie Message Request instead of 0x0203. The errors are due
	to documentation errors with the original implementation of		to documentation errors with the original implementation of
	Autokey. This document marks the erroneous values as reserved, in		Autokey. This document marks the erroneous values as reserved, in
	case there is an implementation using the registered values		case there is an implementation using the registered values
	instead of what the original implementation used. Applications		instead of what the original implementation used. Applications
	that used those values would have realized that they did not		that used those values would have realized that they did not
	interoperate with the dominant (if not only) implementation at the		interoperate with the dominant (if not only) implementation at the
	time. Marking the values as reserved ensures that any such		time. Marking the values as reserved ensures that any such
	applications continue to work as is.		applications continue to work as is.
	* Some values were mistakenly reused.		* Some values were mistakenly reused.
	2.3. Network Time Security Registries		2.3. Network Time Security Registries
	[RFC8915] defines the NTS protocol. The related registries are		[RFC8915] defines the NTS protocol. The related registries are
	listed here for completeness, but there are no changes specified in		listed here for completeness, but there are no changes specified in
	this document.		this document.
	In [RFC8915]:		In [RFC8915]:
	Sections 7.1 through 7.5 (inclusive) added entries to existing		Sections 7.1 through 7.5 (inclusive) added entries to existing
	registries.		registries.
	Section 7.6 created the "Network Time Security Key Establishment		Section 7.6 created the "Network Time Security Key Establishment
	Record Types" registry that partitions the range into three different		Record Types" registry that partitions the range into three different
	registration policies: IETF Review, Specification Required, and		registration policies: IETF Review, Specification Required, and
	Private or Experimental Use.		Private or Experimental Use.
	Section 7.7 created the "Network Time Security Next Protocols"		Section 7.7 created the "Network Time Security Next Protocols"
	registry that similarly partitions the range.		registry that similarly partitions the range.
	Section 7.8 created the "Network Time Security Error Codes" and		Section 7.8 created the "Network Time Security Error Codes" and
	"Network Time Security Warning Codes" registries. Both registries		"Network Time Security Warning Codes" registries. Both registries
	are partitioned the same way.		are partitioned the same way.
	3. Registry Updates		3. NTP Registry Updates
	The following general guidelines apply to the NTP registries:		The following general guidelines apply to the NTP registries:
	* Each registry reserves a partition for Private or Experimental		* A partition of the "NTP Extension Field Types" registry is
	Use.
	* Entries with ASCII fields are now limited to uppercase letters or
	digits; fields starting with 0x58, the uppercase letter "X", are
	reserved for Private or Experimental Use.		reserved for Private or Experimental Use.
	* The policy for every registry is now Specification Required, as		* In the "NTP Reference Identifier Codes" and "NTP Kiss-o'-Death
			Codes" registries, entries with ASCII fields are now limited to
			uppercase letters or digits. Fields starting with 0x58, the
			uppercase letter "X", are reserved for Private or Experimental
			Use.
			* The policy for each registry is now Specification Required, as
	defined in [RFC8126], Section 4.6.		defined in [RFC8126], Section 4.6.
			3.1. Designated Experts
	The IESG is requested to choose three designated experts (DEs), with		The IESG is requested to choose three designated experts (DEs), with
	approvals from two being required to implement a change. Guidance		approvals from two being required to implement a change. Guidance
	for the experts is given below.		for the experts is given below.
	3.1. Guidance to Designated Experts
	The DEs should be familiar with [RFC8126], particularly Section 5.		The DEs should be familiar with [RFC8126], particularly Section 5.
	As that reference suggests, the DE should ascertain the existence of		As that reference suggests, the DE should ascertain the existence of
	a suitable specification and verify that it is publicly available.		a suitable specification and verify that it is publicly available.
	The DE is also expected to check the clarity of purpose and use of		The DE is also expected to check the clarity of purpose and use of
	the requested code points.		the requested code points.
	In addition, the DE is expected to be familiar with this document,		In addition, the DE is expected to be familiar with this document,
	specifically the history documented here.		specifically the history documented here.
	4. IANA Considerations		4. IANA Considerations
	Each entry described in the subsections below is intended to		Each entry described in the subsections below is intended to
	completely replace the existing entry with the same name.		completely replace the existing entry with the same name.
	4.1. NTP Reference Identifier Codes		4.1. NTP Reference Identifier Codes
	The registration procedure has been changed to Specification Required		The registration procedure has been changed to Specification Required
	and this document has been added as a reference.		and this document has been added as a reference.
	The Note has been changed to read as follows:		The Note has been changed to read as follows:
	| Codes beginning with the character "X" are reserved for		| Codes beginning with the character "X" are reserved for
	| experimentation and development. IANA cannot assign them.		| experimentation and development. IANA cannot assign them.
	The columns are defined as follows:		The columns are defined as follows:
	ID (required): a four-byte value padded on the right with all-bits-		ID (required): a four-byte value padded on the right with all-bits-
	zero. Each byte other than padding must be ASCII uppercase		zero. Each byte other than padding must be ASCII uppercase
	letters or digits.		letters or digits.
	Clock source (required): a brief text description of the ID.		Clock source (required): a brief text description of the ID.
	Reference (required): the publication defining the ID.		Reference (required): the publication defining the ID.
	The existing entries are left unchanged.		The existing entries are left unchanged.
	4.2. NTP Kiss-o'-Death Codes		4.2. NTP Kiss-o'-Death Codes
	The registration procedure is changed to Specification Required and		The registration procedure is changed to Specification Required and
	this document has been added as a reference.		this document has been added as a reference.
	The Note has been changed to read as follows:		The Note has been changed to read as follows:
	| Codes beginning with the character "X" are reserved for		| Codes beginning with the character "X" are reserved for
	| experimentation and development. IANA cannot assign them.		| experimentation and development. IANA cannot assign them.
	The columns are defined as follows:		The columns are defined as follows:
	ID (required): a four-byte value padded on the right with all-bits-		ID (required): a four-byte value padded on the right with all-bits-
	zero. Each byte other than padding must be ASCII uppercase		zero. Each byte other than padding must be ASCII uppercase
	letters or digits.		letters or digits.
	Meaning source (required): a brief text description of the ID.		Meaning source (required): a brief text description of the ID.
	Reference (required): the publication defining the ID.		Reference (required): the publication defining the ID.
	The existing entries are left unchanged.		The existing entries are left unchanged.
	4.3. NTP Extension Field Types		4.3. NTP Extension Field Types
	The registration procedure has been changed to Specification Required		The registration procedure has been changed to Specification Required
	and [RFC5906] and this document have been added as references.		and [RFC5906] and this document have been added as references.
	The following two Notes have been added:		The following two Notes have been added:
	| Field Types in the range 0xF000 through 0xFFFF, inclusive, are		| Field Types in the range 0xF000 through 0xFFFF, inclusive, are
	| reserved for experimentation and development. IANA cannot assign		| reserved for experimentation and development. IANA cannot assign
	| them. Both NTS Cookie and Autokey Message Request have the same		| them. Both NTS Cookie and Autokey Message Request have the same
	| Field Type; in practice this is not a problem as the field		| Field Type; in practice this is not a problem as the field
	| semantics will be determined by other parts of the message.		| semantics will be determined by other parts of the message.
	| The "Reserved for historic reasons" is for differences between the		| The "Reserved for historic reasons" is for differences between the
	| original documentation and implementation of Autokey and marks the		| original documentation and implementation of Autokey and marks the
	| erroneous values as reserved, in case there is an implementation		| erroneous values as reserved, in case there is an implementation
	| that used the registered values instead of what the original		| that used the registered values instead of what the original
	| implementation used.		| implementation used.
	The columns are defined as follows:		The columns are defined as follows:
	Field Type (required): a two-byte value in hexadecimal.		Field Type (required): a two-byte value in hexadecimal.
	Meaning (required): a brief text description of the field type.		Meaning (required): a brief text description of the field type.
	Reference (required): the publication defining the field type.		Reference (required): the publication defining the field type.
	IANA has updated the registry as shown in Table 1.		IANA has updated the registry as shown in Table 1.
	+===============+====================================+=============+		+===============+====================================+=============+
	| Field Type | Meaning | Reference |		| Field Type | Meaning | Reference |
	+===============+====================================+=============+		+===============+====================================+=============+
	| 0x0000 | Crypto-NAK; authentication failure | [RFC5905] |		| 0x0000 | Crypto-NAK; authentication failure | [RFC5905] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0002 | Reserved for historic reasons | RFC 9748 |		| 0x0002 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0102 | Reserved for historic reasons | RFC 9748 |		| 0x0102 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0104 | Unique Identifier | [RFC8915], |		| 0x0104 | Unique Identifier | [RFC8915], |
	| | | Section 5.3 |		| | | Section 5.3 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0200 | No-Operation Request | [RFC5906] |		| 0x0200 | No-Operation Request | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0201 | Association Message Request | [RFC5906] |		| 0x0201 | Association Message Request | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0202 | Certificate Message Request | [RFC5906] |		| 0x0202 | Certificate Message Request | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0203 | Cookie Message Request | [RFC5906] |		| 0x0203 | Cookie Message Request | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0204 | Autokey Message Request | [RFC5906] |		| 0x0204 | Autokey Message Request | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0204 | NTS Cookie | [RFC8915], |		| 0x0204 | NTS Cookie | [RFC8915], |
	| | | Section 5.4 |		| | | Section 5.4 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0205 | Leapseconds Message Request | [RFC5906] |		| 0x0205 | Leapseconds Message Request | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0206 | Sign Message Request | [RFC5906] |		| 0x0206 | Sign Message Request | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0207 | IFF Identity Message Request | [RFC5906] |		| 0x0207 | IFF Identity Message Request | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0208 | GQ Identity Message Request | [RFC5906] |		| 0x0208 | GQ Identity Message Request | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0209 | MV Identity Message Request | [RFC5906] |		| 0x0209 | MV Identity Message Request | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0302 | Reserved for historic reasons | RFC 9748 |		| 0x0302 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0304 | NTS Cookie Placeholder | [RFC8915], |		| 0x0304 | NTS Cookie Placeholder | [RFC8915], |
	| | | Section 5.5 |		| | | Section 5.5 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0402 | Reserved for historic reasons | RFC 9748 |		| 0x0402 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0404 | NTS Authenticator and Encrypted | [RFC8915], |		| 0x0404 | NTS Authenticator and Encrypted | [RFC8915], |
	| | Extension Fields | Section 5.6 |		| | Extension Fields | Section 5.6 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0502 | Reserved for historic reasons | RFC 9748 |		| 0x0502 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0602 | Reserved for historic reasons | RFC 9748 |		| 0x0602 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0702 | Reserved for historic reasons | RFC 9748 |		| 0x0702 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0802 | Reserved for historic reasons | RFC 9748 |		| 0x0802 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x0902 | Reserved for historic reasons | RFC 9748 |		| 0x0902 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x2005 | UDP Checksum Complement | [RFC7821] |		| 0x2005 | UDP Checksum Complement | [RFC7821] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8002 | Reserved for historic reasons | RFC 9748 |		| 0x8002 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8102 | Reserved for historic reasons | RFC 9748 |		| 0x8102 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8200 | No-Operation Response | [RFC5906] |		| 0x8200 | No-Operation Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8201 | Association Message Response | [RFC5906] |		| 0x8201 | Association Message Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8202 | Certificate Message Response | [RFC5906] |		| 0x8202 | Certificate Message Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8203 | Cookie Message Response | [RFC5906] |		| 0x8203 | Cookie Message Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8204 | Autokey Message Response | [RFC5906] |		| 0x8204 | Autokey Message Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8205 | Leapseconds Message Response | [RFC5906] |		| 0x8205 | Leapseconds Message Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8206 | Sign Message Response | [RFC5906] |		| 0x8206 | Sign Message Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8207 | IFF Identity Message Response | [RFC5906] |		| 0x8207 | IFF Identity Message Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8208 | GQ Identity Message Response | [RFC5906] |		| 0x8208 | GQ Identity Message Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8209 | MV Identity Message Response | [RFC5906] |		| 0x8209 | MV Identity Message Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8302 | Reserved for historic reasons | RFC 9748 |		| 0x8302 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8402 | Reserved for historic reasons | RFC 9748 |		| 0x8402 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8502 | Reserved for historic reasons | RFC 9748 |		| 0x8502 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8602 | Reserved for historic reasons | RFC 9748 |		| 0x8602 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8702 | Reserved for historic reasons | RFC 9748 |		| 0x8702 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8802 | Reserved for historic reasons | RFC 9748 |		| 0x8802 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0x8902 | Reserved for historic reasons | RFC 9748 |		| 0x8902 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC002 | Reserved for historic reasons | RFC 9748 |		| 0xC002 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC102 | Reserved for historic reasons | RFC 9748 |		| 0xC102 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC200 | No-Operation Error Response | [RFC5906] |		| 0xC200 | No-Operation Error Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC201 | Association Message Error Response | [RFC5906] |		| 0xC201 | Association Message Error Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC202 | Certificate Message Error Response | [RFC5906] |		| 0xC202 | Certificate Message Error Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC203 | Cookie Message Error Response | [RFC5906] |		| 0xC203 | Cookie Message Error Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC204 | Autokey Message Error Response | [RFC5906] |		| 0xC204 | Autokey Message Error Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC205 | Leapseconds Message Error Response | [RFC5906] |		| 0xC205 | Leapseconds Message Error Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC206 | Sign Message Error Response | [RFC5906] |		| 0xC206 | Sign Message Error Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC207 | IFF Identity Message Error | [RFC5906] |		| 0xC207 | IFF Identity Message Error | [RFC5906] |
	| | Response | |		| | Response | |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC208 | GQ Identity Message Error Response | [RFC5906] |		| 0xC208 | GQ Identity Message Error Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC209 | MV Identity Message Error Response | [RFC5906] |		| 0xC209 | MV Identity Message Error Response | [RFC5906] |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC302 | Reserved for historic reasons | RFC 9748 |		| 0xC302 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC402 | Reserved for historic reasons | RFC 9748 |		| 0xC402 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC502 | Reserved for historic reasons | RFC 9748 |		| 0xC502 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC602 | Reserved for historic reasons | RFC 9748 |		| 0xC602 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC702 | Reserved for historic reasons | RFC 9748 |		| 0xC702 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC802 | Reserved for historic reasons | RFC 9748 |		| 0xC802 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xC902 | Reserved for historic reasons | RFC 9748 |		| 0xC902 | Reserved for historic reasons | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	| 0xF000-0xFFFF | Reserved for Experimental Use | RFC 9748 |		| 0xF000-0xFFFF | Reserved for Experimental Use | RFC 9748 |
	+---------------+------------------------------------+-------------+		+---------------+------------------------------------+-------------+
	Table 1		Table 1
	5. Security Considerations		5. Security Considerations
	This document adds no new security considerations, as they are		This document adds no new security considerations, as they are
	defined in the document that defines the extension. See the		defined in the document that defines the extension. See the
	References column of the appropriate IANA registry.		References column of the appropriate IANA registry.
	6. Normative References		6. Normative References
	[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,		[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
	"Network Time Protocol Version 4: Protocol and Algorithms		"Network Time Protocol Version 4: Protocol and Algorithms
	Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,		Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
	<https://www.rfc-editor.org/info/rfc5905>.		<https://www.rfc-editor.org/info/rfc5905>.
	[RFC5906] Haberman, B., Ed. and D. Mills, "Network Time Protocol		[RFC5906] Haberman, B., Ed. and D. Mills, "Network Time Protocol
	Version 4: Autokey Specification", RFC 5906,		Version 4: Autokey Specification", RFC 5906,
	DOI 10.17487/RFC5906, June 2010,		DOI 10.17487/RFC5906, June 2010,
	<https://www.rfc-editor.org/info/rfc5906>.		<https://www.rfc-editor.org/info/rfc5906>.
	[RFC7821] Mizrahi, T., "UDP Checksum Complement in the Network Time		[RFC7821] Mizrahi, T., "UDP Checksum Complement in the Network Time
	Protocol (NTP)", RFC 7821, DOI 10.17487/RFC7821, March		Protocol (NTP)", RFC 7821, DOI 10.17487/RFC7821, March
	2016, <https://www.rfc-editor.org/info/rfc7821>.		2016, <https://www.rfc-editor.org/info/rfc7821>.
	[RFC7822] Mizrahi, T. and D. Mayer, "Network Time Protocol Version 4		[RFC7822] Mizrahi, T. and D. Mayer, "Network Time Protocol Version 4
	(NTPv4) Extension Fields", RFC 7822, DOI 10.17487/RFC7822,		(NTPv4) Extension Fields", RFC 7822, DOI 10.17487/RFC7822,
	March 2016, <https://www.rfc-editor.org/info/rfc7822>.		March 2016, <https://www.rfc-editor.org/info/rfc7822>.
	[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>.
	[RFC8573] Malhotra, A. and S. Goldberg, "Message Authentication Code		[RFC8573] Malhotra, A. and S. Goldberg, "Message Authentication Code
	for the Network Time Protocol", RFC 8573,		for the Network Time Protocol", RFC 8573,
	DOI 10.17487/RFC8573, June 2019,		DOI 10.17487/RFC8573, June 2019,
	<https://www.rfc-editor.org/info/rfc8573>.		<https://www.rfc-editor.org/info/rfc8573>.
	[RFC8915] Franke, D., Sibold, D., Teichel, K., Dansarie, M., and R.		[RFC8915] Franke, D., Sibold, D., Teichel, K., Dansarie, M., and R.
	Sundblad, "Network Time Security for the Network Time		Sundblad, "Network Time Security for the Network Time
	Protocol", RFC 8915, DOI 10.17487/RFC8915, September 2020,		Protocol", RFC 8915, DOI 10.17487/RFC8915, September 2020,
	<https://www.rfc-editor.org/info/rfc8915>.		<https://www.rfc-editor.org/info/rfc8915>.
	Acknowledgements		Acknowledgements
	The members of the NTP Working Group helped a great deal. Notable		The members of the NTP Working Group helped a great deal. Notable
	contributors include:		contributors include:
	* Miroslav Lichvar, Red Hat		* Miroslav Lichvar, Red Hat
	* Daniel Franke, formerly at Akamai Technologies		* Daniel Franke, formerly at Akamai Technologies
	* Danny Mayer, Network Time Foundation		* Danny Mayer, Network Time Foundation
	* Michelle Cotton, formerly at IANA		* Michelle Cotton, formerly at IANA
	* Tamme Dittrich, Tweede Golf		* Tamme Dittrich, Tweede Golf
	Author's Address		Author's Address
	Rich Salz		Rich Salz
	Akamai Technologies		Akamai Technologies
	Email: rsalz@akamai.com		Email: rsalz@akamai.com
End of changes. 6 change blocks.
	11 lines changed or deleted		13 lines changed or added
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