draft-duerst-iri-08.txt		draft-duerst-iri-09.txt
	Network Working Group M. Duerst		Network Working Group M. Duerst
	Internet-Draft W3C		Internet-Draft W3C
	Expires: November 26, 2004 M. Suignard		Expires: January 17, 2005 M. Suignard
	Microsoft Corporation		Microsoft Corporation
	May 28, 2004		July 19, 2004
	Internationalized Resource Identifiers (IRIs)		Internationalized Resource Identifiers (IRIs)
	draft-duerst-iri-08		draft-duerst-iri-09
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, I certify that any applicable		By submitting this Internet-Draft, I certify that any applicable
	patent or other IPR claims of which I am aware have been disclosed,		patent or other IPR claims of which I am aware have been disclosed,
	and any of which I become aware will be disclosed, in accordance with		and any of which I become aware will be disclosed, in accordance with
	RFC 3668.		RFC 3668.
	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 35		skipping to change at page 1, line 35
	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 November 26, 2004.		This Internet-Draft will expire on January 17, 2005.
	Copyright Notice		Copyright Notice
	Copyright (C) The Internet Society (2004). All Rights Reserved.		Copyright (C) The Internet Society (2004). All Rights Reserved.
	Abstract		Abstract
	This document defines a new protocol element, the Internationalized		This document defines a new protocol element, the Internationalized
	Resource Identifier (IRI), as a complement to the Uniform Resource		Resource Identifier (IRI), as a complement to the Uniform Resource
	Identifier (URI). An IRI is a sequence of characters from the		Identifier (URI). An IRI is a sequence of characters from the
	skipping to change at page 2, line 41		skipping to change at page 2, line 41
	5.2 Conversion to URIs . . . . . . . . . . . . . . . . . . . . 23		5.2 Conversion to URIs . . . . . . . . . . . . . . . . . . . . 23
	5.3 Normalization . . . . . . . . . . . . . . . . . . . . . . 23		5.3 Normalization . . . . . . . . . . . . . . . . . . . . . . 23
	5.4 Preferred Forms . . . . . . . . . . . . . . . . . . . . . 24		5.4 Preferred Forms . . . . . . . . . . . . . . . . . . . . . 24
	6. Use of IRIs . . . . . . . . . . . . . . . . . . . . . . . . . 25		6. Use of IRIs . . . . . . . . . . . . . . . . . . . . . . . . . 25
	6.1 Limitations on UCS Characters Allowed in IRIs . . . . . . 25		6.1 Limitations on UCS Characters Allowed in IRIs . . . . . . 25
	6.2 Software Interfaces and Protocols . . . . . . . . . . . . 25		6.2 Software Interfaces and Protocols . . . . . . . . . . . . 25
	6.3 Format of URIs and IRIs in Documents and Protocols . . . . 26		6.3 Format of URIs and IRIs in Documents and Protocols . . . . 26
	6.4 Use of UTF-8 for Encoding Original Characters . . . . . . 26		6.4 Use of UTF-8 for Encoding Original Characters . . . . . . 26
	6.5 Relative IRI References . . . . . . . . . . . . . . . . . 27		6.5 Relative IRI References . . . . . . . . . . . . . . . . . 27
	7. URI/IRI Processing Guidelines (informative) . . . . . . . . . 27		7. URI/IRI Processing Guidelines (informative) . . . . . . . . . 27
	7.1 URI/IRI Software Interfaces . . . . . . . . . . . . . . . 27		7.1 URI/IRI Software Interfaces . . . . . . . . . . . . . . . 28
	7.2 URI/IRI Entry . . . . . . . . . . . . . . . . . . . . . . 28		7.2 URI/IRI Entry . . . . . . . . . . . . . . . . . . . . . . 28
	7.3 URI/IRI Transfer Between Applications . . . . . . . . . . 29		7.3 URI/IRI Transfer Between Applications . . . . . . . . . . 29
	7.4 URI/IRI Generation . . . . . . . . . . . . . . . . . . . . 29		7.4 URI/IRI Generation . . . . . . . . . . . . . . . . . . . . 29
	7.5 URI/IRI Selection . . . . . . . . . . . . . . . . . . . . 30		7.5 URI/IRI Selection . . . . . . . . . . . . . . . . . . . . 30
	7.6 Display of URIs/IRIs . . . . . . . . . . . . . . . . . . . 30		7.6 Display of URIs/IRIs . . . . . . . . . . . . . . . . . . . 31
	7.7 Interpretation of URIs and IRIs . . . . . . . . . . . . . 31		7.7 Interpretation of URIs and IRIs . . . . . . . . . . . . . 31
	7.8 Upgrading Strategy . . . . . . . . . . . . . . . . . . . . 31		7.8 Upgrading Strategy . . . . . . . . . . . . . . . . . . . . 32
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 32		8. Security Considerations . . . . . . . . . . . . . . . . . . . 33
	9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34		9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
	10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 34		10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 34
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . 34		11. References . . . . . . . . . . . . . . . . . . . . . . . . . 35
	11.1 Normative References . . . . . . . . . . . . . . . . . . . . 34		11.1 Normative References . . . . . . . . . . . . . . . . . . . . 35
	11.2 Non-normative References . . . . . . . . . . . . . . . . . . 35		11.2 Non-normative References . . . . . . . . . . . . . . . . . . 36
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 38		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 38
	A. Design Alternatives . . . . . . . . . . . . . . . . . . . . . 38		A. Design Alternatives . . . . . . . . . . . . . . . . . . . . . 39
	A.1 New Scheme(s) . . . . . . . . . . . . . . . . . . . . . . 38		A.1 New Scheme(s) . . . . . . . . . . . . . . . . . . . . . . 39
	A.2 Other Character Encodings than UTF-8 . . . . . . . . . . . 39		A.2 Other Character Encodings than UTF-8 . . . . . . . . . . . 39
	A.3 New Encoding Convention . . . . . . . . . . . . . . . . . 39		A.3 New Encoding Convention . . . . . . . . . . . . . . . . . 39
	A.4 Indicating Character Encodings in the URI/IRI . . . . . . 39		A.4 Indicating Character Encodings in the URI/IRI . . . . . . 40
	Intellectual Property and Copyright Statements . . . . . . . . 40		Intellectual Property and Copyright Statements . . . . . . . . 41
	1. Introduction		1. Introduction
	1.1 Overview and Motivation		1.1 Overview and Motivation
	A Uniform Resource Identifier (URI) is defined in [RFCYYYY] as a		A Uniform Resource Identifier (URI) is defined in [RFCYYYY] as a
	sequence of characters chosen from a limited subset of the repertoire		sequence of characters chosen from a limited subset of the repertoire
	of US-ASCII [ASCII] characters.		of US-ASCII [ASCII] characters.
	The characters in URIs are frequently used for representing words of		The characters in URIs are frequently used for representing words of
	skipping to change at page 9, line 19		skipping to change at page 9, line 19
	irelative-part = "//" iauthority ipath-abempty		irelative-part = "//" iauthority ipath-abempty
	/ ipath-abs		/ ipath-abs
	/ ipath-noscheme		/ ipath-noscheme
	/ ipath-empty		/ ipath-empty
	iauthority = [ iuserinfo "@" ] ihost [ ":" port ]		iauthority = [ iuserinfo "@" ] ihost [ ":" port ]
	iuserinfo = *( iunreserved / pct-encoded / sub-delims / ":" )		iuserinfo = *( iunreserved / pct-encoded / sub-delims / ":" )
	ihost = IP-literal / IPv4address / ireg-name		ihost = IP-literal / IPv4address / ireg-name
	ireg-name = 0*255( iunreserved / pct-encoded / sub-delims )		ireg-name = *( iunreserved / pct-encoded / sub-delims )
	ipath = ipath-abempty ; begins with "/" or is empty		ipath = ipath-abempty ; begins with "/" or is empty
	/ ipath-abs ; begins with "/" but not "//"		/ ipath-abs ; begins with "/" but not "//"
	/ ipath-noscheme ; begins with a non-colon segment		/ ipath-noscheme ; begins with a non-colon segment
	/ ipath-rootless ; begins with a segment		/ ipath-rootless ; begins with a segment
	/ ipath-empty ; zero characters		/ ipath-empty ; zero characters
	ipath-abempty = *( "/" isegment )		ipath-abempty = *( "/" isegment )
	ipath-abs = "/" [ isegment-nz *( "/" isegment ) ]		ipath-abs = "/" [ isegment-nz *( "/" isegment ) ]
	ipath-noscheme = isegment-nzc *( "/" isegment )		ipath-noscheme = isegment-nzc *( "/" isegment )
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	case of using an HTTP proxy.		case of using an HTTP proxy.
	Note: Internationalized Domain Names may be contained in parts of an		Note: Internationalized Domain Names may be contained in parts of an
	IRI other than the ireg-name part. It is the responsibility of		IRI other than the ireg-name part. It is the responsibility of
	scheme-specific implementations (if the Internationalized Domain		scheme-specific implementations (if the Internationalized Domain
	Name is part of the scheme syntax) or of server-side		Name is part of the scheme syntax) or of server-side
	implementations (if the Internationalized Domain Name is part of		implementations (if the Internationalized Domain Name is part of
	'iquery') to apply the necessary conversions at the appropriate		'iquery') to apply the necessary conversions at the appropriate
	point. Example: Trying to validate the Web page at		point. Example: Trying to validate the Web page at
	http://résumé.example.org would lead to an IRI of		http://résumé.example.org would lead to an IRI of
	http://validator.w3.org/check?uri=http%3A%2F%2Frésumé.example.org,		http://validator.w3.org/check?uri=http%3A%2F%2Frésumé.
	which would convert to a URI of		example.org, which would convert to a URI of
	http://validator.w3.org/check?uri=http%3A%2F%2Fr%C3%A9sum%C3%A9.example.org.		http://validator.w3.org/check?uri=http%3A%2F%2Fr%C3%A9sum%C3%A9.
	The server side implementation would be responsible to do the		example.org. The server side implementation would be responsible
	necessary conversions in order to be able to retrieve the Web		to do the necessary conversions in order to be able to retrieve
	page.		the Web page.
	Infrastructure accepting IRIs MAY also deal with the printable		Infrastructure accepting IRIs MAY also deal with the printable
	characters in US-ASCII that are not allowed in URIs, namely "<", ">",		characters in US-ASCII that are not allowed in URIs, namely "<", ">",
	'"', Space, "{", "}", "|", "\", "^", and "`", in Step 2 above. If		'"', Space, "{", "}", "|", "\", "^", and "`", in Step 2 above. If
	such characters are found but are not converted, then the conversion		such characters are found but are not converted, then the conversion
	SHOULD fail. Please note that the number sign ("#"), the percent		SHOULD fail. Please note that the number sign ("#"), the percent
	sign ("%"), and the square bracket characters ("[", "]") are not part		sign ("%"), and the square bracket characters ("[", "]") are not part
	of the above list, and MUST NOT be converted. Protocols and formats		of the above list, and MUST NOT be converted. Protocols and formats
	that have used earlier definitions of IRIs including these characters		that have used earlier definitions of IRIs including these characters
	MAY require percent-encoding of these characters as a preprocessing		MAY require percent-encoding of these characters as a preprocessing
	skipping to change at page 26, line 39		skipping to change at page 26, line 39
	This section discusses details and gives examples for point c) in		This section discusses details and gives examples for point c) in
	Section 1.2. In order to be able to use IRIs, the URI corresponding		Section 1.2. In order to be able to use IRIs, the URI corresponding
	to the IRI in question has to encode original characters into octets		to the IRI in question has to encode original characters into octets
	using UTF-8. This can be specified for all URIs of a URI scheme, or		using UTF-8. This can be specified for all URIs of a URI scheme, or
	can apply to individual URIs for schemes that do not specify how to		can apply to individual URIs for schemes that do not specify how to
	encode original characters. It can apply to the whole URI, or only		encode original characters. It can apply to the whole URI, or only
	some part. For background information on encoding characters into		some part. For background information on encoding characters into
	URIs, see also Section 2.5 of [RFCYYYY].		URIs, see also Section 2.5 of [RFCYYYY].
	For new URI schemes, using UTF-8 is recommended in [RFC2718].		For new URI schemes, using UTF-8 is recommended in [RFC2718].
	Examples where this is already used are the URN syntax [RFC2141],		Examples where UTF-8 is already used are the URN syntax [RFC2141],
	IMAP URLs [RFC2192], and POP URLs [RFC2384]. On the other hand,		IMAP URLs [RFC2192], and POP URLs [RFC2384]. On the other hand,
	because the HTTP URL scheme does not specify how to encode original		because the HTTP URL scheme does not specify how to encode original
	characters, only some HTTP URLs can have corresponding but different		characters, only some HTTP URLs can have corresponding but different
	IRIs.		IRIs.
	For example, for a document with a URI of		For example, for a document with a URI of
	http://www.example.org/r%C3%A9sum%C3%A9.html, it is possible to		http://www.example.org/r%C3%A9sum%C3%A9.html, it is possible to
	construct a corresponding IRI (in XML notation, see Section 1.4):		construct a corresponding IRI (in XML notation, see Section 1.4):
	http://www.example.org/r&#xE9;sum&#xE9;.html (&#xE9; stands for the		http://www.example.org/r&#xE9;sum&#xE9;.html (&#xE9; stands for the
	e-acute character, and %C3%A9 is the UTF-8 encoded and		e-acute character, and %C3%A9 is the UTF-8 encoded and
	percent-encoded representation of that character). On the other		percent-encoded representation of that character). On the other
	hand, for a document with a URI of		hand, for a document with a URI of
	http://www.example.org/r%E9sum%E9.html, the percent-encoding octets		http://www.example.org/r%E9sum%E9.html, the percent-encoding octets
	cannot be converted to actual characters in an IRI, because the		cannot be converted to actual characters in an IRI, because the
	percent-encoding is not based on UTF-8.		percent-encoding is not based on UTF-8.
			This means that for most URI schemes, there is no need to upgrade
			their scheme definition in order for them to work with IRIs. The
			main case where upgrading a scheme definition may make sense is when
			a scheme definition is limited to the use of US-ASCII characters with
			no provision to include non-ASCII characters/octets but a desire to
			include such characters, or only with provisions that are highly
			scheme-specific. An example of such a scheme might be the mailto:
			scheme [RFC2368].
			This specification does not upgrade any scheme specifications in any
			way, this has to be done separately. Also, it should be noted that
			there is no such thing as an "IRI scheme"; all IRIs use URI schemes,
			and all URI schemes can be used with IRIs, even though in some cases
			only by using URIs directly as IRIs, without any conversion.
	The requirement for the use of UTF-8 applies to all parts of a URI		The requirement for the use of UTF-8 applies to all parts of a URI
	(with the potential exception of the ireg-name part, see Section		(with the potential exception of the ireg-name part, see Section
	3.1). However, it is possible that the capability of IRIs to		3.1). However, it is possible that the capability of IRIs to
	represent a wide range of characters directly is used just in some		represent a wide range of characters directly is used just in some
	parts of the IRI (or IRI reference). The other parts of the IRI may		parts of the IRI (or IRI reference). The other parts of the IRI may
	only contain US-ASCII characters, or they may not be based on UTF-8.		only contain US-ASCII characters, or they may not be based on UTF-8.
	They may be based on another character encoding, or they may directly		They may be based on another character encoding, or they may directly
	encode raw binary data (see also [RFC2397]).		encode raw binary data (see also [RFC2397]).
	For example, it is possible to have a URI reference of		For example, it is possible to have a URI reference of
	skipping to change at page 32, line 38		skipping to change at page 33, line 4
	example, when setting up a new file-based Web server, using UTF-8 as		example, when setting up a new file-based Web server, using UTF-8 as
	the character encoding for file names will make the transition to		the character encoding for file names will make the transition to
	IRIs easier. Likewise, when setting up a new Web form using UTF-8 as		IRIs easier. Likewise, when setting up a new Web form using UTF-8 as
	the character encoding of the form page, the returned query URIs will		the character encoding of the form page, the returned query URIs will
	use UTF-8 as the character encoding (unless the user, for whatever		use UTF-8 as the character encoding (unless the user, for whatever
	reason, changes the character encoding) and will therefore be		reason, changes the character encoding) and will therefore be
	compatible with IRIs.		compatible with IRIs.
	These recommendations, when taken together, will allow for the		These recommendations, when taken together, will allow for the
	extension from URIs to IRIs in order to handle characters other than		extension from URIs to IRIs in order to handle characters other than
	US-ASCII while minimizing interoperability problems.		US-ASCII while minimizing interoperability problems. For
			considerations regarding the upgrade of URI scheme definitions,
			please see Section 6.4.
	8. Security Considerations		8. Security Considerations
	The security considerations discussed in [RFCYYYY] also apply to		The security considerations discussed in [RFCYYYY] also apply to
	IRIs. In addition, the following issues require particular care for		IRIs. In addition, the following issues require particular care for
	IRIs.		IRIs.
	Incorrect encoding or decoding can lead to security problems. In		Incorrect encoding or decoding can lead to security problems. In
	particular, some UTF-8 decoders do not check against overlong byte		particular, some UTF-8 decoders do not check against overlong byte
	sequences. As an example, a '/' is encoded with the byte 0x2F both		sequences. As an example, a '/' is encoded with the byte 0x2F both
	skipping to change at page 36, line 21		skipping to change at page 36, line 40
	[Duerst01]		[Duerst01]
	Duerst, M., "Internationalized Resource Identifiers: From		Duerst, M., "Internationalized Resource Identifiers: From
	Specification to Testing", Proc. 19th International		Specification to Testing", Proc. 19th International
	Unicode Conference, San Jose , September 2001,		Unicode Conference, San Jose , September 2001,
	<http://www.w3.org/2001/Talks/0912-IUC-IRI/paper.html>.		<http://www.w3.org/2001/Talks/0912-IUC-IRI/paper.html>.
	[Duerst97]		[Duerst97]
	Duerst, M., "The Properties and Promises of UTF-8", Proc.		Duerst, M., "The Properties and Promises of UTF-8", Proc.
	11th International Unicode Conference, San Jose ,		11th International Unicode Conference, San Jose ,
	September 1997,		September 1997,
	<http://www.ifi.unizh.ch/mml/mduerst/papers/PDF/IUC11-UTF-8.pdf>		<http://www.ifi.unizh.ch/mml/mduerst/papers/PDF/
	.		IUC11-UTF-8.pdf>.
	[Gettys] Gettys, J., "URI Model Consequences",		[Gettys] Gettys, J., "URI Model Consequences",
	<http://www.w3.org/DesignIssues/ModelConsequences>.		<http://www.w3.org/DesignIssues/ModelConsequences>.
	[HTML4] Raggett, D., Le Hors, A. and I. Jacobs, "HTML 4.01		[HTML4] Raggett, D., Le Hors, A. and I. Jacobs, "HTML 4.01
	Specification", World Wide Web Consortium Recommendation,		Specification", World Wide Web Consortium Recommendation,
	December 1999,		December 1999,
	<http://www.w3.org/TR/REC-html40/appendix/notes.html#h-B.2>		<http://www.w3.org/TR/REC-html40/appendix/
	.		notes.html#h-B.2>.
	[RFC2130] Weider, C., Preston, C., Simonsen, K., Alvestrand, H.,		[RFC2130] Weider, C., Preston, C., Simonsen, K., Alvestrand, H.,
	Atkinson, R., Crispin, M. and P. Svanberg, "The Report of		Atkinson, R., Crispin, M. and P. Svanberg, "The Report of
	the IAB Character Set Workshop held 29 February - 1 March,		the IAB Character Set Workshop held 29 February - 1 March,
	1996", RFC 2130, April 1997.		1996", RFC 2130, April 1997.
	[RFC2141] Moats, R., "URN Syntax", RFC 2141, May 1997.		[RFC2141] Moats, R., "URN Syntax", RFC 2141, May 1997.
	[RFC2192] Newman, C., "IMAP URL Scheme", RFC 2192, September 1997.		[RFC2192] Newman, C., "IMAP URL Scheme", RFC 2192, September 1997.
	[RFC2277] Alvestrand, H., "IETF Policy on Character Sets and		[RFC2277] Alvestrand, H., "IETF Policy on Character Sets and
	Languages", BCP 18, RFC 2277, January 1998.		Languages", BCP 18, RFC 2277, January 1998.
			[RFC2368] Hoffman, P., Masinter, L. and J. Zawinski, "The mailto URL
			scheme", RFC 2368, July 1998.
	[RFC2384] Gellens, R., "POP URL Scheme", RFC 2384, August 1998.		[RFC2384] Gellens, R., "POP URL Scheme", RFC 2384, August 1998.
	[RFC2396] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform		[RFC2396] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
	Resource Identifiers (URI): Generic Syntax", RFC 2396,		Resource Identifiers (URI): Generic Syntax", RFC 2396,
	August 1998.		August 1998.
	[RFC2397] Masinter, L., "The "data" URL scheme", RFC 2397, August		[RFC2397] Masinter, L., "The "data" URL scheme", RFC 2397, August
	1998.		1998.
	[RFC2616] Fielding, R., Gettys, J., Mogul, J., Nielsen, H.,		[RFC2616] Fielding, R., Gettys, J., Mogul, J., Nielsen, H.,
End of changes.
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