rfc9485.txt		rfc9485-stdtags.txt
	skipping to change at line 81 ¶		skipping to change at line 81 ¶
	(abbreviated as "regexp") flavor, I-Regexp.		(abbreviated as "regexp") flavor, I-Regexp.
	I-Regexp does not provide advanced regular expression features such		I-Regexp does not provide advanced regular expression features such
	as capture groups, lookahead, or backreferences. It supports only a		as capture groups, lookahead, or backreferences. It supports only a
	Boolean matching capability, i.e., testing whether a given regular		Boolean matching capability, i.e., testing whether a given regular
	expression matches a given piece of text.		expression matches a given piece of text.
	I-Regexp supports the entire repertoire of Unicode characters		I-Regexp supports the entire repertoire of Unicode characters
	(Unicode scalar values); both the I-Regexp strings themselves and the		(Unicode scalar values); both the I-Regexp strings themselves and the
	strings they are matched against are sequences of Unicode scalar		strings they are matched against are sequences of Unicode scalar
	values (often represented in UTF-8 encoding form [RFC3629] for		values (often represented in UTF-8 encoding form [STD63] for
	interchange).		interchange).
	I-Regexp is a subset of XML Schema Definition (XSD) regular		I-Regexp is a subset of XML Schema Definition (XSD) regular
	expressions [XSD-2].		expressions [XSD-2].
	This document includes guidance for converting I-Regexps for use with		This document includes guidance for converting I-Regexps for use with
	several well-known regular expression idioms.		several well-known regular expression idioms.
	The development of I-Regexp was motivated by the work of the JSONPath		The development of I-Regexp was motivated by the work of the JSONPath
	Working Group (WG). The WG wanted to include support for the use of		Working Group (WG). The WG wanted to include support for the use of
	skipping to change at line 337 ¶		skipping to change at line 337 ¶
	libraries in severely constrained environments may not be able to		libraries in severely constrained environments may not be able to
	support I-Regexp conformance.		support I-Regexp conformance.
	7. IANA Considerations		7. IANA Considerations
	This document has no IANA actions.		This document has no IANA actions.
	8. Security Considerations		8. Security Considerations
	While technically out of the scope of this specification, Section 10		While technically out of the scope of this specification, Section 10
	("Security Considerations") of [RFC3629] applies to implementations.		("Security Considerations") of RFC 3629 [STD63] applies to
	Particular note needs to be taken of the last paragraph of Section 3		implementations. Particular note needs to be taken of the last
	("UTF-8 definition") of [RFC3629]; an I-Regexp implementation may		paragraph of Section 3 ("UTF-8 definition") of RFC 3629 [STD63]; an
	need to mitigate limitations of the platform implementation in this		I-Regexp implementation may need to mitigate limitations of the
	regard.		platform implementation in this regard.
	As discussed in Section 6, more complex regexp libraries may contain		As discussed in Section 6, more complex regexp libraries may contain
	exploitable bugs, which can lead to crashes and remote code		exploitable bugs, which can lead to crashes and remote code
	execution. There is also the problem that such libraries often have		execution. There is also the problem that such libraries often have
	performance characteristics that are hard to predict, leading to		performance characteristics that are hard to predict, leading to
	attacks that overload an implementation by matching against an		attacks that overload an implementation by matching against an
	expensive attacker-controlled regexp.		expensive attacker-controlled regexp.
	I-Regexps have been designed to allow implementation in a way that is		I-Regexps have been designed to allow implementation in a way that is
	resilient to both threats; this objective needs to be addressed		resilient to both threats; this objective needs to be addressed
	skipping to change at line 444 ¶		skipping to change at line 444 ¶
	ietf-jsonpath-base-20>.		ietf-jsonpath-base-20>.
	[PCRE2] "Perl-compatible Regular Expressions (revised API:		[PCRE2] "Perl-compatible Regular Expressions (revised API:
	PCRE2)", <http://pcre.org/current/doc/html/>.		PCRE2)", <http://pcre.org/current/doc/html/>.
	[RE2] "RE2 is a fast, safe, thread-friendly alternative to		[RE2] "RE2 is a fast, safe, thread-friendly alternative to
	backtracking regular expression engines like those used in		backtracking regular expression engines like those used in
	PCRE, Perl, and Python. It is a C++ library.", commit		PCRE, Perl, and Python. It is a C++ library.", commit
	73031bb, <https://github.com/google/re2>.		73031bb, <https://github.com/google/re2>.
	[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
	10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
	2003, <https://www.rfc-editor.org/info/rfc3629>.
	[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>.
			[STD63] Yergeau, F., "UTF-8, a transformation format of ISO
			10646", STD 63, RFC 3629, November 2003.
			<https://www.rfc-editor.org/info/std63>
	[UNICODE-GLOSSARY]		[UNICODE-GLOSSARY]
	Unicode, Inc., "Glossary of Unicode Terms",		Unicode, Inc., "Glossary of Unicode Terms",
	<https://unicode.org/glossary/>.		<https://unicode.org/glossary/>.
	Acknowledgements		Acknowledgements
	Discussion in the IETF JSONPATH WG about whether to include a regexp		Discussion in the IETF JSONPATH WG about whether to include a regexp
	mechanism into the JSONPath query expression specification and		mechanism into the JSONPath query expression specification and
	previous discussions about the YANG pattern and Concise Data		previous discussions about the YANG pattern and Concise Data
	Definition Language (CDDL) .regexp features motivated this		Definition Language (CDDL) .regexp features motivated this
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