rfc9907v4.txt		rfc9907.txt
	skipping to change at line 974 ¶		skipping to change at line 974 ¶
	}		}
	leaf ipv6-site-of-origin {		leaf ipv6-site-of-origin {
	type rt-types:ipv6-route-origin;		type rt-types:ipv6-route-origin;
	description		description
	"The IPv6 Site of Origin attribute is encoded as an IPv6		"The IPv6 Site of Origin attribute is encoded as an IPv6
	Route Origin Extended Community. It is meant to uniquely		Route Origin Extended Community. It is meant to uniquely
	identify the set of routes learned from a site.";		identify the set of routes learned from a site.";
	reference		reference
	"RFC 5701";		"RFC 5701";
	}		}
	}
	3.10. Validation Tools		3.10. Validation Tools
	All modules need to be validated before submission in an I-D. The		All modules need to be validated before submission in an I-D. The
	'pyang' YANG compiler is freely available from GitHub:		'pyang' YANG compiler is freely available from GitHub:
	<https://github.com/mbj4668/pyang>.		<https://github.com/mbj4668/pyang>.
	If the 'pyang' compiler is used to validate a normative module, then		If the 'pyang' compiler is used to validate a normative module, then
	the "--ietf" command-line option MUST be used to identify any IETF		the "--ietf" command-line option MUST be used to identify any IETF
	guideline issues.		guideline issues.
	skipping to change at line 1001 ¶		skipping to change at line 1000 ¶
	command "pyang -f yang --keep-comments --yang-line-length 69" should		command "pyang -f yang --keep-comments --yang-line-length 69" should
	be used.		be used.
	The "yanglint" program is also freely available from GitHub:		The "yanglint" program is also freely available from GitHub:
	<https://github.com/CESNET/libyang>.		<https://github.com/CESNET/libyang>.
	This tool can be used to validate "XPath" statements within YANG		This tool can be used to validate "XPath" statements within YANG
	modules.		modules.
	To check that JSON-encoded examples [RFC7951] comply with the target		To check that JSON-encoded examples [RFC7951] comply with the target
	data models, programs such as "yangson" or "yanglint" should be used.		data models, programs such as 'yangson' or 'yanglint' should be used.
	Both programs are freely available from GitHub: <https://github.com/		Both programs are freely available from GitHub: <https://github.com/
	CZ-NIC/yangson> and <https://github.com/CESNET/libyang>.		CZ-NIC/yangson> and <https://github.com/CESNET/libyang>.
	3.11. Module Extraction Tools		3.11. Module Extraction Tools
	A version of 'rfcstrip' that will extract YANG modules from an I-D or		A version of 'rfcstrip' that will extract YANG modules from an I-D or
	RFC is freely available at: <https://github.com/mbj4668/rfcstrip>.		RFC is freely available at: <https://github.com/mbj4668/rfcstrip>.
	This tool can be used to verify that the "<CODE BEGINS>" and "<CODE		This tool can be used to verify that the "<CODE BEGINS>" and "<CODE
	ENDS>" tags are used correctly and that the normative YANG modules		ENDS>" tags are used correctly and that the normative YANG modules
	skipping to change at line 2408 ¶		skipping to change at line 2407 ¶
	4.18. YANG Data Node Constraints		4.18. YANG Data Node Constraints
	4.18.1. Controlling Quantity		4.18.1. Controlling Quantity
	The "min-elements" and "max-elements" statements can be used to		The "min-elements" and "max-elements" statements can be used to
	control how many list or leaf-list instances are required for a		control how many list or leaf-list instances are required for a
	particular data node. YANG constraint statements SHOULD be used to		particular data node. YANG constraint statements SHOULD be used to
	identify conditions that apply to all implementations of the data		identify conditions that apply to all implementations of the data
	model. If platform-specific limitations (e.g., the "max-elements"		model. If platform-specific limitations (e.g., the "max-elements"
	supported for a particular list) are relevant to operations, then a		supported for a particular list) are relevant to operations, then a
	data model "definition" statement (e.g., "max-ports" leaf) SHOULD be		data model definition statement (e.g., "max-ports" leaf) SHOULD be
	used to identify the limit.		used to identify the limit.
	4.18.2. "must" versus "when"		4.18.2. "must" versus "when"
	"must" and "when" YANG statements are used to provide cross-object		"must" and "when" YANG statements are used to provide cross-object
	referential tests. They have very different behavior. The "when"		referential tests. They have very different behavior. The "when"
	statement causes data node instances to be silently deleted as soon		statement causes data node instances to be silently deleted as soon
	as the condition becomes false. A false "when" statement is not		as the condition becomes false. A false "when" statement is not
	considered to be an error.		considered to be an error.
	skipping to change at line 2432 ¶		skipping to change at line 2431 ¶
	list key leafs).		list key leafs).
	The "must" statement causes a datastore validation error if the		The "must" statement causes a datastore validation error if the
	condition is false. This statement SHOULD be used for enforcing		condition is false. This statement SHOULD be used for enforcing
	parameter value restrictions that involve more than one data node		parameter value restrictions that involve more than one data node
	(e.g., end-time parameter must be after the start-time parameter).		(e.g., end-time parameter must be after the start-time parameter).
	4.19. "augment" Statements		4.19. "augment" Statements
	The YANG "augment" statement is used to define a set of data		The YANG "augment" statement is used to define a set of data
	"definition" statements that will be added as child nodes of a target		definition statements that will be added as child nodes of a target
	data node. The module namespace for these data nodes will be the		data node. The module namespace for these data nodes will be the
	augmenting module, not the augmented module.		augmenting module, not the augmented module.
	A top-level "augment" statement SHOULD NOT be used if the target data		A top-level "augment" statement SHOULD NOT be used if the target data
	node is in the same module or submodule as the evaluated "augment"		node is in the same module or submodule as the evaluated "augment"
	statement. The data "definition" statements SHOULD be added inline		statement. The data definition statements SHOULD be added inline
	instead.		instead.
	4.19.1. Conditional Augment Statements		4.19.1. Conditional Augment Statements
	The "augment" statement is often used together with the "when"		The "augment" statement is often used together with the "when"
	statement and/or "if-feature" statement to make the augmentation		statement and/or "if-feature" statement to make the augmentation
	conditional on some portion of the data model.		conditional on some portion of the data model.
	The following example from [RFC8343] shows how a conditional		The following example from [RFC8343] shows how a conditional
	container called "ethernet" is added to the "interface" list only for		container called "ethernet" is added to the "interface" list only for
	skipping to change at line 2522 ¶		skipping to change at line 2521 ¶
	}		}
	}		}
	}		}
	Note that this practice is safe only for creating data resources. It		Note that this practice is safe only for creating data resources. It
	is not safe for replacing or modifying resources if the client does		is not safe for replacing or modifying resources if the client does
	not know about the new condition. The YANG data model MUST be		not know about the new condition. The YANG data model MUST be
	packaged in a way that requires the client to be aware of the		packaged in a way that requires the client to be aware of the
	mandatory data nodes if it is aware of the condition for this data.		mandatory data nodes if it is aware of the condition for this data.
	In the example above, the "some-new-iftype" identity is defined in		In the example above, the "some-new-iftype" identity is defined in
	the same module as the "mandatory-leaf" data "definition" statement.		the same module as the "mandatory-leaf" data definition statement.
	This practice is not safe for identities defined in a common module		This practice is not safe for identities defined in a common module
	such as "iana-if-type" because the client is not required to know		such as "iana-if-type" because the client is not required to know
	about "my-module" just because it knows about the "iana-if-type"		about "my-module" just because it knows about the "iana-if-type"
	module.		module.
	4.20. Deviation Statements		4.20. Deviation Statements
	Per Section 7.20.3 of [RFC7950], the YANG "deviation" statement is		Per Section 7.20.3 of [RFC7950], the YANG "deviation" statement is
	not allowed to appear in IETF YANG modules, but it can be useful for		not allowed to appear in IETF YANG modules, but it can be useful for
	skipping to change at line 3084 ¶		skipping to change at line 3083 ¶
	Authors can use existing standard tags or use new tags defined in the		Authors can use existing standard tags or use new tags defined in the
	model definition, as appropriate. For IETF modules, new tags MUST be		model definition, as appropriate. For IETF modules, new tags MUST be
	assigned in the IANA "IETF YANG Module Tags" registry within the		assigned in the IANA "IETF YANG Module Tags" registry within the
	"YANG Module Tags" registry group [IANA-TAGS].		"YANG Module Tags" registry group [IANA-TAGS].
	4.29. Modeling Abstract Data Structures		4.29. Modeling Abstract Data Structures
	For contexts where YANG is used to model abstract data structures		For contexts where YANG is used to model abstract data structures
	(e.g., protocol messages), the use of the "structure" extension		(e.g., protocol messages), the use of the "structure" extension
	statement [RFC8791] is RECOMMENDED compared to the "yang-data"		statement [RFC8791] is RECOMMENDED compared to the "yang-data"
	"extension" statement [RFC8040]. Examples of modules that rely upon		extension statement [RFC8040]. Examples of modules that rely upon
	the "structure" extension statement from [RFC8791] can be found in		the "structure" extension statement from [RFC8791] can be found in
	[RFC9132] or [RFC9195].		[RFC9132] or [RFC9195].
	Abstract data structures can be augmented using the "augment-		Abstract data structures can be augmented using the "augment-
	structure" statement [RFC8791]. Examples of modules that augment		structure" statement [RFC8791]. Examples of modules that augment
	abstract data structures can be found in [RFC9244] and [RFC9362].		abstract data structures can be found in [RFC9244] and [RFC9362].
	4.30. IANA-Maintained YANG Modules		4.30. IANA-Maintained YANG Modules
	4.30.1. Context		4.30.1. Context
	skipping to change at line 3295 ¶		skipping to change at line 3294 ¶
	with the naming conventions listed in Section 4.3.1, IANA		with the naming conventions listed in Section 4.3.1, IANA
	should check if guidance to generate legal identifiers was		should check if guidance to generate legal identifiers was
	supplied in the RFC that specified the initial version of the		supplied in the RFC that specified the initial version of the
	module. If no such guidance is available, IANA should check		module. If no such guidance is available, IANA should check
	the latest revision of the IANA-maintained YANG module for		the latest revision of the IANA-maintained YANG module for
	similar patterns. If all else fails, IANA should seek advice		similar patterns. If all else fails, IANA should seek advice
	from relevant registry experts (e.g., designated experts for a		from relevant registry experts (e.g., designated experts for a
	registry using the Expert Review policy (Section 4.5 of		registry using the Expert Review policy (Section 4.5 of
	[RFC8126]) or responsible area director).		[RFC8126]) or responsible area director).
			The IANA Considerations Section MAY also provide the following
			information if a default action is expected:
	* A note whether unassigned or reserved values should be present in		* A note whether unassigned or reserved values should be present in
	the IANA-maintained YANG module. If no instruction is provided,		the IANA-maintained YANG module. If no instruction is provided,
	unassigned or reserved values must not be present in the IANA-		unassigned or reserved values must not be present in the IANA-
	maintained YANG module.		maintained YANG module.
	* An instruction whether experimental values should be included in		* An instruction whether experimental values should be included in
	the IANA-maintained YANG module. If no instruction is provided,		the IANA-maintained YANG module. If no instruction is provided,
	experimental values MUST NOT be listed in the IANA-maintained YANG		experimental values MUST NOT be listed in the IANA-maintained YANG
	module.		module.
End of changes. 8 change blocks.
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