rfc9100v3.txt		rfc9100.txt
	Internet Engineering Task Force (IETF) C. Bormann		Internet Engineering Task Force (IETF) C. Bormann
	Request for Comments: 9100 Universität Bremen TZI		Request for Comments: 9100 Universität Bremen TZI
	Updates: 8428 July 2021		Updates: 8428 August 2021
	Category: Standards Track		Category: Standards Track
	ISSN: 2070-1721		ISSN: 2070-1721
	Sensor Measurement Lists (SenML) Features and Versions		Sensor Measurement Lists (SenML) Features and Versions
	Abstract		Abstract
	This short document updates RFC 8428, "Sensor Measurement Lists		This short document updates RFC 8428, "Sensor Measurement Lists
	(SenML)", by specifying the use of independently selectable "SenML		(SenML)", by specifying the use of independently selectable "SenML
	Features" and mapping them to SenML version numbers.		Features" and mapping them to SenML version numbers.
	skipping to change at line 113 ¶		skipping to change at line 113 ¶
	The present specification defines "SenML Features", each identified		The present specification defines "SenML Features", each identified
	by a "feature name" (a text string) and a "feature code" (an unsigned		by a "feature name" (a text string) and a "feature code" (an unsigned
	integer less than 53).		integer less than 53).
	The specific version of a SenML pack is composed of a set of		The specific version of a SenML pack is composed of a set of
	features. The SenML version number ("bver" field) is then a bitmap		features. The SenML version number ("bver" field) is then a bitmap
	of these features represented as an unsigned integer, specifically		of these features represented as an unsigned integer, specifically
	the sum of, for each feature present, two taken to the power of the		the sum of, for each feature present, two taken to the power of the
	feature code of that feature (Figure 1).		feature code of that feature (Figure 1).
	__ 52 fc		__ 52 fc
	version = \ present(fc) ⋅ 2		version = \ present(fc) ⋅ 2
	/__ fc = 0		/__ fc = 0
	Figure 1: Feature Bitmap as a Sum (Sigma Symbol) of Feature Bits		Figure 1: Feature Bitmap as a Sum (Sigma Symbol) of Feature Bits
	where present(fc) is 1 if the feature with the feature code "fc" is		where present(fc) is 1 if the feature with the feature code "fc" is
	present, 0 otherwise. (The expression 2^fc can be implemented as "1		present, 0 otherwise. (The expression 2^fc can be implemented as "1
	<< fc" in C and related languages.)		<< fc" in C and related languages.)
	2.1. Discussion		2.1. Discussion
	skipping to change at line 319 ¶		skipping to change at line 319 ¶
	7.2. Informative References		7.2. Informative References
	[RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493,		[RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493,
	DOI 10.17487/RFC7493, March 2015,		DOI 10.17487/RFC7493, March 2015,
	<https://www.rfc-editor.org/info/rfc7493>.		<https://www.rfc-editor.org/info/rfc7493>.
	Acknowledgements		Acknowledgements
	Ari Keränen proposed to use the version number as a bitmap and		Ari Keränen proposed to use the version number as a bitmap and
	provided further input on this specification. Jaime Jiménez helped		provided further input on this specification. Jaime Jiménez helped
	clarify the document by providing a review. Elwyn Davies provided a		clarify the document by providing a review and acted as Document
	detailed GENART review with directly implementable text suggestions		Shepherd. Elwyn Davies provided a detailed GENART review with
	that now form part of this specification. Rob Wilton supplied		directly implementable text suggestions that now form part of this
	comments, one of which became the last paragraph of Section 2.1; Éric		specification. Rob Wilton supplied comments, one of which became the
	Vyncke helped with Section 2. Additional thanks go to the other IESG		last paragraph of Section 2.1; Éric Vyncke helped with Section 2.
	reviewers.		Additional thanks go to the other IESG reviewers.
	Author's Address		Author's Address
	Carsten Bormann		Carsten Bormann
	Universität Bremen TZI		Universität Bremen TZI
	Postfach 330440		Postfach 330440
	D-28359 Bremen		D-28359 Bremen
	Germany		Germany
	Phone: +49-421-218-63921		Phone: +49-421-218-63921
End of changes. 3 change blocks.
	8 lines changed or deleted		8 lines changed or added
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